You may well be able to run them, but it will run like a dog (IMO). If you are planning to run it as a server, I'd forget about using a gui at all - it will run quicker that way - you might also want to think about upgrading the memory
www.crucial.com are my personal preferred supplier for memory. They deliver pretty quickly and have a tool to help you work out which memory is the best.
If you do need a gui, I'd go for a nice lightweight one like Flux or IceWM.