This time it's confirmed!
Midway and Epic have released the system requirements for UT3, and it doesn't look half bad. Especially since you've already upgraded your rig for Crysis.
Minimum System Requirements
* Windows XP SP2 or Windows Vista
* 2.0+ GHZ Single Core Processor
* 512 Mbytes of System
RAM
* NVIDIA 6200+ or ATI Radeon 9600+ Video Card
* 8 GB of Free Hard Drive Space
Recommended System Requirements
* 2.4+ GHZ Dual Core Processor
* 1 GBytes of System
RAM
* NVIDIA 7800GTX+ or ATI x1300+ Video Card
* 8 GB of Free Hard Drive Space