The PC2700 is going to be alright for now. If you plan on doing some heavy gaming (and I mean heavy), you are going to need more than just the average 400 Mhz (PC3200). I would strongly recommend going for some High Performance memory, like Corsair XMS, or Corsair XMS PRO (if you want to go all out).
The Corsair XMS PRO is unbelievable. It is quite expensive (512 Mb of XMS PRO costs more than 1 Gb of XMS), but IMO it is worth the price. I just bought some of it (C2 (OC'd) version), and I couldn't believe my eyes. This memory is the king. If you don't have the money right now... This would be a great investment.