Ive used SU and kerky on vista on my friends PC without problems. Another friend of mine is using 64 bit vista and he also has no troubles with it.
Someone who is very good with computers wouldnt have any issue getting things to work with vista, and many of the problems are being patched in SP1.
And as a correction, a 32 bit OS can and will handle up to 4GB of memory in total. Im dead sure about this. This amount will be taken up by your GFX card's memory, and any other devices which use memory addresses. The reason im dead sure of this is because this friend whom i use his Vista PC for SU once in a while also has a XP machine with 4GBs of ram in it, with exactly 3.21 usable (512 MB gfx card takes some of the total access up) And im positive it is a 32 bit OS because im the one who ordered it and installed it for him.
You are right about the application needing to be 64 bit to use more RAM, and in fact on 32 bit you cannot use more than 2GB at a time for an application. But you can have up to 4GBs of ram, all of which is usable. The thing is, XP doesnt like to let the applications use all available RAM, because it reserves some for itself. I have been on more than one 4GB PC where almost every bit of RAM is being used at some point.
Also you typed that up sort of wrong.
2,147,483,648Mb = 2,147,483,648,000,000 bits which equals 268,435,456,000,000 bytes or 268 GBs so i think there was an error there. 32 bits is equal to 429,4967,296 possible combinations of 1 and 0. You missed one more multiple, 31 bits is equal to 2,147,483,648.
You were one short of 64 bits also. 64 bits is equal to 18,446,744,073,709,551,616 possible combinations of 1 and 0.
The name for that number is Exobytes, meaning 18 Exobytes are possible, it goes Giga Tera, Peta, Exo if im not mistaken.