[DDR PC3200] Mixing ram stick sizes?

[SiD the Turtle]

Hey guys. I bought 2x1Gb DDR PC3200 for my brother for Christmas, to upgrade his P4 from 512Mb of RAM to 2Gb. The question is that I still have two free slots and the two old 256Mb sticks spare.

Now before I go and experiment, will the old sticks work alongside the new ones, giving him 2.5Gb of RAM? Are there any downsides to this?

 

[SiD the Turtle]

Thanks for the advice guys. I did give it a try and it won't even boot with all four in even if I play with the various RAM settings, so two sticks it is!