DDR Ram is the most commen ram used currently, In both AMD and Intel. So i would reccomend getting about 512 of DDR 333 thats becoming the standard. In regards to what you will need to upgrade, you will need a MObo, CPU, heatsink/fan, ram. Depending on how old your current system is you may have to upgrade your Power supply to P4/xp complient. But besides that you should be good to go.. =Drewdatrip