Attached Link: http://support.microsoft.com/default.aspx?scid=kb;en-us;833721#XSLTH3239121121120121120120

There is a per process memory limit of 2GB. There is a switch that can increase this to 3GB (see attached link), but I've also seen a mention that not all programs are capable of taking advantage of it YMMV.

Take sensible precautions if your messing about with these, if you don't have a techie on hand, best to leave well alone.