What to do what to do????

Ok, right now in my a7n8x, i have a single stick of 512MB pc2700. Im running my athlon xp 1700 at 12.5X166 to get 2600+ speeds and a 333fsb. Im thinking of buying 2 512MB sticks of pc3200. This way, i would have 1.5GB of ram. Here is my question, would my system perform better with 1.5GB or memory in 333fsb at 2600+ speeds, or would it perform better with 1GB of mem in 400 fsb and a higher clocked cpu? So to get 1.5Gb of mem at 2600 333, or 1GB of mem at higher, 2.2ghz+?

oh and, what would be better for me to get to upgrade this system, here is my specs:

AMD Athlon XP 1700 @ 2600+
512MB PC2700 DDR
ATI Radeon 9000 Pro 128MB

what would i benefit more from, getting a rad 9600 pro and oc'in the crap out of it(water cooling hehe) or getting another gig of memory? THey both cost about the same and 160 bucks is my budget. I game the vast majority of the time.