Maybe try Openbox instead of XFCE. Can’t promise it’ll add much memory but with 1gb RAM I guess every bit counts?
Edit: just had a quick look around, and it looks like your machine can be upgraded to a whopping 2gb RAM… It’s still not great, but it is a 100% increase in memory.
Edit 2: I’m not actually recommending you buy RAM from memorystock.com, it just turned up at the top of my search results. The page should give you the type and version you’ll need to look for, though.