Can i use different DDR sticks at the same time (PC2100/3200/2700/etc)

Basically a newb question, but yeah. Can i use different DDR sticks at the same time. Such as using 256 mb of PC2100 ram and 256 mb of PC2700 at the same time. Is there any disadvantage to this?

[golfcart]

In theory it will all just run at the speed of the lowest rated stick. In the real world there may be incompatibility issues. Only way to know for sure is to try it

I agree. Should work but at lower speed.