Why do you come on a Windows XP forum if all you want is to uninstall everything from MS on it? Anyway...
I don't see why you should uninstall OE 6. Just learn to setup Internet Options properly (*cough* Programs tab *cough*). If you change the default mail program there, you can set it to whatever you like, depending on what you have installed.
If you're a netscape fan, ask yourself why. If your answer is only "because I hate mycrosoft", then think again. NETSCAPE SUCKS! Oh sorry, did I say that loud? Netscape WAS better than IE wayyyy back when we had IE 3 and Netscape 4. As soon as they started releasing their Communicator versions, and now.. Netcrap 6 (from AOL by the way), it's more messy than ever and IE is WAY more stable, and supports twice the amount of script and technologies Netscape does.
FYI, 70% of the browsers on the web are IE natives. Netscape is dying! If you don't want to use IE, at least use OPERA! It's WAY better than Netscape.
For email, I suggest Eudora 5.1 (free at
www.qualcomm.com). It's stable, has a LOT of features and I like the interface. That's what I'm using now.
If you start uninstalling some core MS programs like IE or OE, you'll find that some other programs will stop from working properly. I'm not saying everything, but some of them. So do it at your own risk, but on XP, IE (which is linked to OE by the way) comes preinstalled, and you can't remove it simply.. It's kind of very complicated. So do it at your own risk.