IMO yes. The GT is worth buying over the 6800, but the ultra is not really worth buying over the GT.
But it depends on what games you play, what resolution your monitor supports and what resolution you want to game at, and also, what detail settings and eye candy you hope to play at. The plain 6800 doesn't do very well at high resolution with AA & AF turned on. It actually falls behind a Radeon 9800XT from last generation at those settings. If you hope to play all the newcoming games at 1280x1024 or above, and use AA/AF, I'd say get the GT as the plain 6800 might(WILL) fall short.
EDIT:
For example, in Farcry look at this review. The 6800's framerates are unacceptable at 1280x1024 with 4XAA/8XAF. And 1600x1200, forget about it. There is a pretty big jump going from the 6800 to the GT, Ultra, or the X800's.
<A HREF="http://www.firingsquad.com/hardware/far_cry_sm30/page8.asp" target="_new">http://www.firingsquad.com/hardware/far_cry_sm30/page8.asp</A>
ABIT IS7, P4 2.6C, 1GB Corsair XMS 4000 Pro Series, Radeon 9800 Pro, Santa Cruz, TruePower 430watt<P ID="edit"><FONT SIZE=-1><EM>Edited by Pauldh on 07/12/04 05:40 PM.</EM></FONT></P>