RAM disk for Vista 64-bit
Solution 1:
The excellent free Gavotte Ramdisk has been updated for 64 bit, but I'm not sure if there's an authoritative source. You can find it by searching.
Here's a 64 bit commercial ramdisk (free up to 400MB): http://www.cenatek.com/product_page_ramdisk.php
-Adam
Solution 2:
I would use a real RAM drive: a USB memory stick.
Solution 3:
ImDisk Virtual Disk Driver 1.4.0 (released in Dec 2010):
The install package is created using 7-zip sfx stubs and includes an .inf install script. No reboot is required after installing or uninstalling. The install package works on Windows NT 3.51/NT 4.0/2000/XP/Server 2003/Vista/Server 2008, both 32-bit and 64-bit versions.
64-bit versions share source code with the 32-bit version. All features and most limitations are the same in the 64-bit and 32-bit versions. One notable difference however is that the 64-bit versions do not have any practical size limits for RAM disks.
64 bit drivers are now digitally signed with a certificate trusted by Microsoft. This means that ImDisk now works Windows Vista, Windows Server 2008 and Windows 7 even without running it testsigning mode.