I have an old computer that I am using as the children's computer, and yesterday I upgraded the RAM from 64 MB to 256 MB. That went fine, but the only thing is, in the system information, the computer has always said it had 63 MB of RAM, even though the old simm says 64 MB. And now it says 255 MB, even though the 2 simms I added are both 128 MB.

Everything works fine, no problems, but I'm curious about that extra 1 MB that's "missing". Where did it go?

I haven't looked at this issue very closely, but it is probably some memory used by the motherboard in the bios or similar. Many computers have onboard graphics cards that will share 32Mb or 64Mb, in effect stealing it from the main system memory. This is probably what is happening here, either with the graphics or some other device!

Hehehehe, I've always had the same issue with my older Compaq boxes.
They all have 256 Mb, but read as 255 Mb.
I think it has something to do with older Bios versions and larger amounts or RAM.
I wouldn't worry about it, after all what's 1 Mb between friends ;)