Finally i have managed to get my workstation working. I bought it from Ebay about 6 weeks ago and had some issues with network drivers and graphics drivers and have been trying to sort it out, finally i managed to resolve the conflicts and get the beastie up and working.
It's a Dell Precision 470 Workstation:- 2* Xeon 3.2GHz 800MHz 2*2MB HT CPU's with 4GB PC2 4600DDR II
It took a little configuring in my preferences (once I realised that the problem was there) but it is now running 4 Einstein work units simultaneously with an estimated crucnh time of 35 hours a piece, though I reckon they will do in about 14 hours based on the other machines..
That should help me build a decent RAC in a reasonable time