Disable any service you don't need, like Automatic Updates, Themes, Security Center, Secondary Login, Wireless Zero Configuration, Indexing Service, Help and Support, Fast User Switching, etc. I was able to get XP running smoothly on a P2 266MHz laptop with 128mb of ram by disabling every non-essential service. If you are only going to use it for word processing and e-mail there are a lot of services that you don't need.