http://www.tortoisecvs.org/ - TortoiseCVS makes the PITA cvs workable under windows explorer nicely, combined with putty+ssh is real good.
http://www.jpsoft.com - 4NT best CMD replacement bar none
http://www.scootersoftware.com/dl.html - Beyond Compare 2 for file comparision
http://www.cosmigo.com/promotion/ Pro Motion the best DPAINT replacement on the PC, great for doing game and low res art tonnes better than photoshop
http://www.sourceoffsite.com Makes sourcesafe work over the internet properly.
http://www.numega.com boundschecker and softice nuff said
http://www.sysinternals.com for lots of good tools
and yes flashget and DC rocks, honourable mentions debabilizer pro, filezilla for ftp(or leechftp)