Dear Granny
From your name, I'll venture it's been a while since you had to sit through a math class

Yes, 4 gigs would be the limit on a typical 32-bit-buss mother board. As you know, everything computing is based on
binary. Binary gives us two options, 0 or 1. And with a 32-bit buss the maximum number of combinations (addresses reachable) would be 2 raised to the 32nd power:
2^32 = 4,294,967,296So, that's 4 gigs for Granny

And if you go for the 64-bit board and OS, you'd have
2^64which gives a whopping
18,446,744,073,709,551,616 Bytes
18 k. tera bytes !(I'm clueless what it's short name is ... 18 Z Bytes? 18
Zillion Bytes)
I'd guess that'd be enough for you and all your grandchildren's children - at least until Linux-128 arrives

Please let us know how this turns out - I'm interested in mucho memory for a project.
cheers,
- Scruf