Projecting a spherical panorama onto a cube is certainly a RAM-intensive operation, so maybe 2 gigabytes isn't going to cut it. I will say that 32-bit Windows is capable of using up to 4 gigabytes of RAM, if you want to make a smaller investment and just upgrade your current machine.
That will still only allow 32-bit Windows to give 32-bit apps (like ICE) 2 gigs of physical RAM to share while the operating system uses the other two, but if you've enabled the maximum size for Windows' paging file, each app will be given a 4 gig virtual memory space and whatever won't fit in physical RAM will be written to the paging file on your hard disk. There's even a setting for Windows where you can switch the RAM balance for 32-bit Windows so that Windows uses 1 gig for itself and uses 3 gigs of physical RAM for apps. I don't know for a fact that 32-bit ICE is written to take advantage of that 3GB switch, though.