I use Gimp.
Gimp is very good. I have never used photoshop, and I probably never will. I find it very easy and slick to use, Although that is probably because that is all I use. I find a good replacement for Adobe Illustrator is InkScape. Oh another one for replacing photo shop is Paint.net.
Have a look at the free version of Art Rage as well.
Alternative to Microsoft office there isn't really a decent one in my opinion but you can use openoffice.org which i heard is quite good.
Here is some recommendations from me that I use.
Microsoft Security Essentials -Recent Release
Blender-I'm not very good at it.
VlC Media player
Any Video Converter
Phun - an Awesome Physics Illustrator
Windows Live Movie Maker
Windows Live Photo Gallery
I know some of these are in other posts ,but I really like them.
Have a look at these links
Alternatives to Adobe — ONE/Northwest
Free Software List for Vista - Vista Forums
Phew, Hope that Helps.