Upgrade macpro 1.1 from 32 bit to 64 bit

The only path available is to install some developer-level hacks designed for Hackintosh [non-Apple Hardware hacked to run Mac OS X illegally]. Unless you think like a hobbyist or developer, these can be quite complex to set up and keep running.

Apple does not condone or support these hacks, and we are discouraged from providing recipes here.

Wait for a new Mac MIni...

You will always have EFI 32-bit even if you upgraded to 5355s and MacPro 2,1 firmware.

If you are up for it, google, there seem to be lots of tools and places to help or discuss this.

Lion for me is fine and luckily is still supported. Mavericks is still "young" and I am sure drivers and support can only improve. ML? I guess if you are faced with having to use or buy or upgraded Pages or something and App Store doesn't .. but you shoudl be using Lion - a good transition to anything higher, dropped Rosetta.

And put your system on an SSD was for me the best $100 in return on performance.

Amazon has had 8 x 2GB FBDIMMs for $100 which is a close second.

A new gpu for $250, glad I did it before the ATI 5770 was sold out though PC 68xx are a 2nd option there.