I recently converted my Dell XPS 420 from Vista x32 Ultimate to Vista x64 Ultimate SP1 (Dell shipped me the correct DVD when I asked for the 4th time). Obviously, a lot of stuff doesn’t work out-of-the box, but a little research did wonders:

Alternatives:

• Cisco VPN -> Shrew Soft VPN (64 bit optimized)
• CanoScan Toolbox & Drivers -> VueScan

Optimized for 64 bit:

• 7-Zip
• Firefox (called Minefield)
• Internet Explorer (installed with OS)
• MediaCoder
• Adobe Illustrator CS4, Acrobat 9, Photoshop CS4,
• K-Lite CODEC Pack
• NVIDIA drivers
• iTunes
• Paint.NET
• Logitech SetPoint

Doesn’t work in 64 bit:

• Flash on 64 bit browser (you need to use the 32 bit browser)
• Plugins for 64 bit FireFox (IE Tab)
• Cisco VPN
• Dell drivers that make icons look like the flash drive they represent (i.e., they all appear as Removable Disk, versus SD-card, etc.)