2 computer setup a possibility

Hey guys, I am toying with the idea of a 2 computer setup for my sim. I currently have: Fs2004 with some great Airport addons, active sky 6 , LVLD767, SB etc. Sorry if I'm going over old ground but my world was shattered the other day when my DE TH2GO failed to work properly. Looking now at serious alternative to keep project moving If i can't resolve the Th2Go issue.

Current Computer.

Intel Duo Core 2 E6600 clocked to 2.7ghz
Gainward overclcoked 8800GT 512mb Dual output DVI
3.2 Gig Ram (xp 32 bit)
360 Gig HDD

:with this computer I have Fs2004 sliders maxed out at 1680x1050 res and achieve high frame rates.

I would like to use up to 4 screens (1 of those a split from cpts monitor). From threads I have read some people are using old pentium 3's and 4's etc as second computers. Realistically what sort of cheap second hand computer and gpu would suit as a second machine and are they easy to network?

If i can't get my Th2go to work I'm thinking of running this

Computer 1: e6600
Forward visuals (Projector) @ 1280x1024
Touchscreen Overhead 22 inch

Computer2: ?
Cptns monitor/split FO
Middle screen (engines etc)
Active sky, Squawkbox, plus any other programs needed for networking.

The cheaper the second computer the better, providing it will fulfill the job and keep the smooth frame rates.

Anyone have some idea as a guide?
Thanks a million for any help.
Drewsta