I am planning on upgrading my comp I've currently got an MSI kt4v mobo running an AMD 2200xp with PC2700 333mhz ram I'm thinking of purchasing an MSI K8N Neo4-F and an Athlon 64 3400 now what i'm wondering is can I use my existing ram on this setup and upgrade it later on or am i going to have to purchase the ram right away. Also is there a special type of 400mhz ram i should be looking at like dual channel? and whats this DDR2 stuff? Is it something I should be looking into? Any info would be a great help.