Im going to go against the grain and say GF2 MX dual head.
The new nView in the 27.xx drivers are what clinch it for me as being able to play games without having to disable the second display, being able to play video on second display, regular driver updates, software side on a par with Matrox nearly IMO, yadda, yadda.

I think Matrox may at last have got a serious competitor with nVidia looking at these drivers.
If you do get an MX dual head, make sure it is an Elsa as they are the only ones with decent 2D from my experience.
Im currently using a PCI Elsa dual head with 2x TFT's and wont be replacing it till the Ti4600 comes down in price end of the year.
Im also biased against ATI cards as ive owned 2 of them and wont be giving them my money again. You may guess why
Edit: How did i do guys, trying to be a nVidia zealot? Shame on me
Oh yeah, i wouldnt recommend buying the MX for the nView till we get a official driver release as there are a couple of bugs in the beta's:-
NAV gives error at clicking finished at end of manual single file scan.
Desktop Explorer disables Windows Explorer!
My MS eBook gives me an error when i close it.
None of these bring the rig down though.
Just to show im not being biased
