You should have 4 slots. For dual channel support, you populate in pairs....same spec RAM in each color coded slot. It would probably be best to have all the same and these are generally offered in matched pairs. As such, you would need 2 matched 2 gig pairs (which is the same as saying 4 1 gig modules. That would max your PC and make your wallet much lighter as well.
i have e machines t6212 running win xp with 512mb ram pc3200 at 400mz two ddr channels it says i need to do it in pairs can i do two 512s or do i need to do it in 256s i want to max it out but not sure what i need full specs on the machine is 2ghz athlon64 3200+ 512 ram ddr sdram ati radeon xpress200 160 gb hard drive

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