I gave background and reasons-- skip to the list if wish for a summary****
I hope I'm not answering a one year old question as the dates I see have no years on them and it is now late 2010. I have the Black Macbook 2,1 also and I did both upgrades. I went from 2gb RAM to 4 gb RAM and upgraded from Tiger to Snow Leopard.
I did some research via the various forums, wiki, and even apple (thank you Google!). From what I have read, the gen macbooks take a max 3gb but 4 gb is fine because there is extra ram that you don't see the computer using. And it is best to upgrade using two sticks of the same amount (2x2gb=4gb or 2x1.5=3gb) to take advantage of dual channels.
SnowLeopard-- The best reason to upgrade is that you can now take advantage of the 64bit processing (vs 32 bit). The Core2Duo is 64bit! Other reasons are very nice tweaks in the programs. Another is I no longer have a problem with finding/logging onto the college's wifi network. I could list more... but google/ search can do that for me. OH AND IT'S ONLY 30 BUCKS!
Personal opinion: The last Mac I personally had was a Performa series back in the late 1990s so I too am returning to Macs. Just because this is an older mac doesn't mean it is the outdated one. The Core2Duo is 64bit capable, the SL (SnowLeopard) takes advantage of the 64bit. 4 gb RAM is the current standard (look in the best buy ad). Programs are still trying to switch over to 64bit. The 2,1 macbook will stay viable for many more years.
1.Back up data
2.Do a clean install which means wiping the HD (look up the user "bullychris" or search keywords "clean install snow leopard" on youtube for a very nice how-to.
3.Upgrade RAM to 3gb or 4gb **DUAL CHANNEL (try to stick with mainstream companies). It's PC5300 So-Dimm.
4.After the SL install do a software update search by going to Appple>about mac>software update . This will take care of the majority of updates for drivers and what not. IE you should be able to use the programs already found one the Mac for media. Other wise search for the Mac version of the media programs you liked using on the PC.
5.Enjoy. *sorry if my message may come as a bit condescending or snooty, wanted to write it for the general Random internet searcher as well as for the OP).
notes Do one or the other upgrade separately so you know what went wrong if something does go wrong. Clean installs are usually best if you're a computer guy, you'll know if you're not a computer guy-- search. SNOW-LEOPARD IS ONLY 30 BUCKS!