the 2 times ur memory for swap is for older *nix systems (e.g. SunOS).. For newer Linux OS if ur physical memory is large enough you wudnt even need a swap space.
This is because swapping is actually causing your system to run slower (RAM read/write is way faster than disk read/write and ur swap is on a disk).

However if u think the applications that u run needs more memory than the physical memory can provide, just add in the swap space of your desire size.
Ideally it is best,for newer Linux OS,to have your swap size the same as your RAM size ; 2 or even 3 times more than ur RAM for older *nix system

ahhh actually there is this super grub disk to help u fix the grub bootloader IF by chance u installed windows first OR by chance your grub/grub2 bootloader failed at some point after installation.
have a look here superGrubdisk

do note that for Ubuntu 9.04 AND before it uses Grub while 9.10 AND onwards uses Grub2