memory upgrade compatibility

[hi99]

Windows XP, Dell Optiplex GX260 desktop with 1-stick 1GB PC3200 400MHz CL3 in it.
Manual says it takes PC2100 266 MHZ up to 2GB max. I want to upgrade by adding a 2nd 1GB stick. Is it OK to add 1GB PC2100 with the PC3200 already installed, or should I add another PC3200, or should I change out to 2-sticks of PC2100 = 2GB? I think if 400MHz and 266MHz are installed together, PC will run at 266MHz speed regardless. I'm just not tech savvy enough to know what PC3200 vs PC2100 is all about with regard to my Dell. Thanks

[Geek-9pm]

That shroud work.
Check you manual. I believe it says you can use higher speed memory and the system drops to the lower speed for both chips.

[soybean]

Manual says it takes PC2100 ...

But, you have PC 3200 installed.      I suggest you visit crucial.com and use their Memory Advisor™ tool to see what memory modules are compatible with your computer.  Since you have PC 3200, I would get another of the same if crucial.com confirms it will work with your system.