Although the Dell's are made by Lexmark, internally they are "coded" as Dell's rather than Lexmark's.  In most cases, if you use a Lexmark driver with a Dell it will not "find" a Lexmark product. 

The major downfall of 64 bit is the lack of drivers for many devices.  64 bit is becoming more popular and eventually it will be the "standard" instead of 32 bit and all new hardware will have 64 bit drivers.  I've avoided 64 bit on my new Q6600 CPU machine for just that reason.

Thanks for the info on the Internal "coding" - that's what I assume was happening.

Is there any way to trick the AIO 960 into working with the Lexmark drivers?

I have a Q6600 also, and while I have 4GB of RAM in the box now, I know it's not all being utilized in 32-bit Vista (I also have another 4GB just hanging out and ready to go for the 64-bit installation if I get everything running).

No way that I know of unless you can find a hacked driver somewhere.  Do a google search, no telling what you will find. 

The ink cartridges are the same way, they are made by Lexmark (or a Lexmark sub-contractor) but the internal IC chip in the ink cartridge is coded as a Dell or Lexmark so they are not interchangeable even tho they are phsically identical.