i would also like to suggest these
all of them are free btw

meebo - a great alternative to aim and msn and icq and all of the stuff. it basically consolidates all of those chat screens into one nice, neat window. no ads.

lavasoft adaware - great spyware/malware scanner

irfanview - allows you to view any type of picture format out there. an extremely "light" program. (wont install any of that crap onto your computer)

firefox - nough said