In the past, I've had a bit of experience trying to install and run ramdisks in Windows XP, but I never found anything really good. Microsoft provided a ramdisk driver for Windows 2000 that one could get working in XP, but it wasn't really useful because it only provided a maximum of 32 MB of storage (Why ?!). I decided to revisit the issue of ramdisks at work today for Windows 7 because I wanted a way to speed up Visual Studio's caching and other operations (and Eclipse, but that's another matter). After searching around some more, I found a program called ImDisk. The installation is dead easy (if a little lacking in the notification department to tell you it's successfully installed). What's even better, you can make disks of arbitrary size, have it simulate various kinds of devices, and you can setup multiple ramdisks. The only catch is that you have to start the service in Administrator mode, and it's a bit more than trivial, though it is easy using the following steps :
1. Start -> All Programs -> Accessories -> Command Prompt -> Right-click -> Run as administrator
2. sc config imdisk start= auto (note the space between start= and auto, this got me the first time)
3. net start imdisk
4. Open up Control Panel -> ImDisk Virtual Disk Driver
... and have at it!