The best RAM is IMHO:
Samsung (on authentic Samsung PCB)
Crucial
Corsair
Mushkin
Kingston
Geil
OCZ
TwinMOS (I really don't know about them)
I'd get any PC2700 (yes, it's the same thing as DDR333) from any of the top 5 or 6 companies. Personally, as long as it isn't Generic RAM, I have no problem buying it. I just got two sticks of Geil's 256MB PC3500 Ultra Platinum. They're great, and they're extremely cheap for the speeds they run at. Be very careful with Samsung because since many resellers know that Samsung has such a great reputation, they'll advertise RAM as being "genuine" Samsung, when actually, it's only Samsung chips on a generic PCB, and that's no better than any other generic stick of RAM. Most of the time, there isn't a problem with putting x RAM into y motherboard, but every once in awhile, there are irreconcilable differences (sounds like a divorce, don't it?) that prevent x RAM from working in y motherboard. I've never had this happen and don't know anyone that this has happened to, I just know that it's a ridiculously small possibility. That's why the REALLY good manufacturers (a.k.a. Crucial and Corsair) post compatibility charts on their websites. It lists what modules have been tested with different motherboards and verifies that they work together. For Crucial, just go to the left side of their main site
here to get their list of approved boards, and for Corsair, go to their compatibility lab
here.