Ph4Zed, it's still worth going for the 4Gb even for 32bit OS, although you will not be able to access the full amount (I think you get roughly 3.5Gb). This is especially useful when you run many applications or memory intensive applications.
As most have pointed out, memory is so cheap nowadays that you might as well go for it, whether you want 32bits or 64bits OS, that'll down to how new your setup will be and be able to find the drivers.
In recent Computer Shoppers article, it seems that more and more people are moving to 64bits, hopefully, this will make hardware companies to provide more 64bits driver.