For those using CVS or SVN looking for a decent client, I can recommend the Tortoise clients (i.e. TortoiseCVS and TortoiseSVN) in conjunction with WinMerge.

Although they mightn't have all the features as something like WinCVS the do the job just fine for us and are very easy to use with integrated shell menus for all commands.

At least with clients you can try them out but keep using your standard client at the same time.

Looks like I might investigate SVN as long is it can import CVS with full histories etc. However CVS does seem to be working OK for us - our repository is only about 2500 files currently and we only have about 4 developers actively using it.