Ness,
unless you actually like overlap, a single 20" (1600x1200) LCD is >>>>>>>> any number of 19" or 17" (1280x1024) LCDs.
If you only play Party, resize lets you fit 4+ tables on any monitor - 9 fit comfortably on a 2001FP.
Here are some screens to show the difference:
(click to view full size images)
19" LCD, no resize 4 tables (nasty overlap)
19" LCD, resized to fit - Party/Empire only
20" LCD, no resize - 4 tables, sweet - no overlap
20" LCD, resized to fit - can do 9 tables if you like
IMHO, 20" or larger flat panels are very much EV+ [img]/images/graemlins/smile.gif[/img] If you can't stretch to one and are considering a 19" or 17" LCD - downgrade other components just to get the monitor, it is the component you are very likely to use the most, after all.
Right about now you can probably pick up the old Dell 2001FP for much cheaper than the new 2007FP - this is a good thing to do, the new one is more expensive and allegedly not as good with colour gradients (noticable watching DVDs etc).
As others have said, any new computer should fine, so long as it has enough RAM (1GB is plenty) and can drive two monitors (Dual DVI video card).
One of the new dual-core CPUs will almost make sure it never lags, but may well take you over budget.
I hope this helps,
dave.