PowerEdge SC600 memory upgrade

One of my clients has a Dell PowerEdge SC600 P4 server that they use as the backbone for their business. Today I visited on site to review a complaint regarding virtual memory errors, severe slowdowns and having to reboot the server after a major printjob. The first thing I saw when I logged onto the server was that they are running a 3 disc raid array that has a 4GB C: parbreastion and a 116GB D:parbreastion. The OS is Windows 2000 and after having that installed along with basic other software, they are down to 384MB remaining free on the C:parbreastion. Basically the virtual memory has no place left to go.

We had a discussion on how to solve this and I suggested that what they are asking of their server in general, they need to upgrade beyond the 512MB single stick of memory that they have in there now to possibly max out the server with 4 x 1GB sticks. However on Dells website, PC2100-ECC-Registered is listed at $274 per 1GB stick. My question is, can I goto newegg or tigerdirect and get them PC2100-ECC-Registered memory at around $150 per stick instead? Does dell run different voltage for memory? Anything I need to be aware of?

Brad