At the risk of insulting the folks of this forum
(by mentioning a "competitor"), there is a guide for turning a 9800Pro into a FireGL X2. It is available at:
Adrian Rojak Pot's Radeon 9800 to FireGL-X2 Guide
It seems pretty straight forward and doesn't even require a BIOS mod if you use the drivers they recommend.
You won't have the 2 - DVI outputs that the "real"
FireGL X-2 has and I think there's a couple of other caveats as well.
One think to keep in mind is that "they" (Adrian Rojak Pot's people) don't think you can mod the 9800NP/Pro if it has the R350 core and several people here have done some pretty amazing things w/R350 cores.
I haven't done the procedure yet myself though I'm going to--like you I'm not a gamer and want the dual monitor desktop performance. I'll let you all know how it goes.
Take care,
Jim
"Guam: Where America's Day Begins!"