I found that we can't install Windows to the bootcamp partition without an external SuperDrive (could this only applies to MacOSX Lion?), normal external optical drive just don't work. Whenever booting up with the external windows DVD installer will resulted a black screen with a blinking cursor. For Mac Mini and MacBook Air which rely on an external optical drive will need to create a USB thumb window installer from the Boot Camp Assistant in order to install the Window OS. We can also download the boot camp drivers through the Boot Camp Assistant utility and burn into a Boot Camp driver installer CD or DVD.

Yes, the Boot Camp driver can be saved into the USB thumb which contains the window ISO file as well. My Mac mini only took less than half an hour for the window 7 installation, maybe my Mac Mini comes with 8GB ram. Since the formatting took so long time, we can might as well format the boot camp partition again with the Disk Utility by selecting NTFS (compressed) format before the Window Installation, then the Window installation process can be perform without formatting the partition.

You mean the Installation+Formating+Installing driver? I can understand the whole process will take merely an hour.
I have tried timing the booting time for the Boot Camp Window 7 on my mini, it took around 65 seconds to boot up completely. Not yet try on Virtual Box before, maybe will give it a try or I should purchase Parrarel Desktop by running in Coherence Mode.

Virtual Box is better than BootCamp? Afaik, Boot Camp are running natively so for performance wise Boot Camp are definately the winner. Parallel Desktop are much improve with the latest version preferable you have more Ram to applies on it. It have the option to transfer the windows os directly from a PC, install a new window os or clone from the Boot Camp to run as mirroring and the best part it runs in Coherence mode. Maybe I am expecting too much on the Window performance which running on a Mac but I am satisfied with the performance of the Boot Camp or Parallel Desktop so far.

Well, as for the underscore you experienced doesn't happen to my Mac Mini 2011. Booting from Boot Camp are just like normal PC and it only took me 65 seconds to boot completely into the Window Desktop. By the way I am running on Window 7 Ultimate 32 bit(since some of my connected device not supporting 64 bit).

You need to install the Boot Camp Drivers to your Window 7 after the installation, to download the Boot Camp Driver just launch the Boot Camp Assistant on your Mac and there's an option to download the drivers. After downloading you may either save it to a thumb drive or burn a Boot Camp driver DVD to use it for the Window 7 driver installation.

You don't have to buy the ultimate Edition of Window 7 just for Microsoft office, Home edition will suffice and if you are a student you can purchase the student copy of Microsoft Office which comes with 3 user. No sure what's the total amount after bundle with the Parallel Desktop but at east it can be the cheaper, otherwise forget about the virtual mode and run Window natively with BootCamp.

Depends on what you want to do with your PC environment, for Microsoft Office only will be suffice enough with 20GB. If you deciding to install Adobe applications or PC games then you have to apply more GB to your BootCamp partition.

Yes, you do need a Window 7 installer DVD for the BootCamp installation process. Here's the procedure for the installation process:

1) Launch BootCamp Assistant from your MacOSX lion and choose your desire partition space with the slider.
2) next you will be prompt to download the bootcamp driver from the Internet to burn into a DVD/CD or save it into an external drive, choose your desire option;
3) once the above process completed, you will be prompt to insert the Window 7 installer DVD.
4) the DVD will load as normal window installation process and you will be prompt to install at which partition, choose the bootcamp partition and select format. Due to NTFS licensing, the bootcamp partition was created with FAT format but Window 7 need to be install into a NTFS formatted drive. Therefore by selecting 'Format' the partition will automatically formatted into an NTFS format, choose the newly formatted drive and click next to start the Window 7 installation.
5) The installation process will start and as normal procedure where you need to choose your language, region and your serial number.
6) after the installation completed you will log into the window, insert the bootcamp DVD driver or the external drive where you saved the downloaded driver to install the driver.
7) that's it and start enjoy your newly install bootcamp window 7.

If you are installing a 32bit Window 7 in the BootCamp, 4GB is enough since 32bit can only supported up to 3.5 GB ram while a 64 bit a Window 7 can support more above 4GB. Technically, 64 bit environment are much better in terms of speed and more ram are better for multitasking, applications speed and UI performance.

I encountered this problem while downloading using my friend Macbook Pro, I found out that whenever the MacOSX falls into sleep mode the dowloading will stalled and not able to continue. Not sure this apply to the same problem you encountering but try off the sleep mode to "never" and retry downloading again.

You can directly use a window installer disc to install the window onto the Bootcamp preferable you perform the Bootcamp installation method correctly. If your window installer comes with just a file, convert it as an iso image and burn to a DVD disc or Pendrive. If I am not mistaken, 2010 model of Mac can't support Pendrive window installation but a 2011 model can.