Here's a general rule of thumb from someone who builds custom systems for individuals and businesses every day for a living:

If you want to know how well a given application, or game, or sim runs on any given system, just have the sales dweeb LOAD the app on the box he's hawking to you and see for yourself how it runs! Bring in your disk and keycode, your input device you plan to use, and test it. No substitute for a real-world test. Use the same model monitor you are looking to buy too, in the case of a LCD monitor, because all LCD's are not the same. If the sales dweeb won't let you, then maybe you don't want to buy from him. This means he's got something to hide. You are talking about a lot of money for that system in the first post (WAAAAY overkill for RF G2, by the way). A 1 GHz Athlon with 128 MB DDR RAM, and an older NVidia GeForce 2 w/64 MB and running Win 98SE runs it beautifully, no choppiness whatsoever at normal resolutions. I know, because that's what I run mine on. Much more speed and power than that is simply overkill for G2, and is money spent purely for bragging rights, IMHO.
Of course, as a PC salesman, I'd be glad to sell you some expensive bragging rights if you feel like you have to have 'em.

Rick