wait GTX2 is that supposed to be GX2 or GTX+ or GTS 250?
BTW the GTX 260 and 9800GTX both require 2 power connectors.
The 4850 requires only one
The GTS 250 is a 9800GTX+ maybe a tiny bit faster, but many if not all of them only require 1 power connectors...all of the 1GB for sure only need 1 connector
It would depend on specific games as to which is faster. From what I have seen the GTS 250 1GB is generally faster than the HD4850 and the HD4850 is generally faster than the GTS 250 512MB.
From the prices I am seeing on newegg (not exactly the best guage for around the world prices) THe GTS 250 512MB and the HD4850 are about the same price ($130) and the GTS 250 1GB is about $20-$30 more than both of those. ($150-$160)