We're currently using WinCVS but it's slow and has no merge dialog. I'm looking for something like Eclipse's Team Synchronize (so people can see what they'll get before they update).
What do you suggest? TortoiseCVS with WinMerge?
Note: OSS preferred :)
On windows, definitely using Tortoise CVS and WinMerge will meet your needs. I also think it would be a good idea to learn how to do some operations with the command line too.