First of all many thanks to all 6400 users to kindly answer my questions, really appreciate it
1. I think I'd most probably go with 80GB HDD and get myself another external one to be safe then.

Buying an external drive should be safer than upgrading the laptop's HDD, no? Btw, I have the Nov booklet from Dell that's valid till Dec 4 and they're offering T5500, but when I check online it's T2050? Also, I couldn't find the option to customise the graphic card online..
2. Yeap you're right they will partition 20GB to C and the rest to D drive, but you can choose if you want 40/60GB in C drive as well. Since it's really easy like you guys say then I'll attempt to do it myself. I can ask for help here if anything goes wrong

3. I definitely can wait since I'll be leaving next February, just thought of getting one now and play around with it first. I thought about PC fair because I heard they usually throw in extra stuff to attract people to buy? And it's good to look around at other brands like HP and Toshiba as well, though their prices are usually above my budget unfortunately. So for PC fairs they only accept cash huh? If that's the case then I'll most probably order through phone/online.
One last thing, my mom in US just e-mailed me and asked if this Toshiba system is worth it. After conversion it's quite cheap ($750=RM2850, offer=$650=RM2470). Compared to 6400, would this be a better deal?
Toshiba Satellite1) Call dell and ask for the processor.
2) Partition it yourself, it is pretty easy.
3) PC fair do accept credit card. My parent just help me bought one for my gf last pc fair.
Compare the spec with dell, see which one better is getting the same spec. And also the outlook of the laptop.