If you are a college student, check and see if your university has an agreement with MS for really low cost software for students. The university I work for also has agreements with Macromedia and a few other companies (statistical software, Autocad, etc.) That can save you a bundle.
My list of must have software:
MS Office
iLife
Adobe Photoshop Elements (espically if you do anything with graphics)
Quicken
For myself, I add FileMaker Pro to that list, but that's just me...
EDIT: And just for future reference you really didn't need to start two threds (this one and one of what notebook to get). You'll probably find it is the same people answering both threads!