the "pc 2700, pc 2100, pc 1600" are the speeds of the RAM you need the same speed ram as what you have now e.g pc3200 with pc3200 or pc2700 with pc2700,to find out what u have,you need to take out u r ram and have a look at the labe and it will tell you something like pc3200,u need to get RAM that has the same speed ,so i f your RAM was PC2700 u would buy pc2700 RAM.And a good graphics card is would be
This one,
this one ,Basically you need one that is PCI and a good brand like,Nvidia or ATI then u need one with a good memory,at the moment im guessing u r using 64mb,for gaming a 256 Mb graphics card would be good.Also you can upgrade yuor processor to get more speed out of your computer.