Thanks for the replies--can't do a pc upgrade anytime soon. I'm looking for something that will reliably let me capture streaming video using Camtasia or something like it. I'll check out the links--i like the idea of spending less than $100

It sucks that my $300 video card from a few yrs ago is worthless, but i guess that's how it goes.
That would be, what, $70 a year? If you got a 7600GT, instead, you would have already upgraded by now, and at best, evened out in terms of total cost up to now. A 7800GT, when it was new, was a pretty good buy.
Thanks! Any good dual 24" monitor stands (desk attached)?
Something like that, for video capture, is going to be bound almost entirely by CPU & RAM. If it's not fast enough now, new mobo+CPU+RAM would have been the way to go, instead of a new monitor. Unfortunately, there is no useful info on the Techsmith website, regarding what kind of system will be really be needed, for what features you may want to use (they even say they have a recommended set of system requirements, but no link to it, it does not come up in a search, and does not appear to be mentioned in any docs).
In that case, a GT 240
DDR5 will have good support for video
decode offloading, with quite a few playback applications, closed and FOSS, will handle high res well, and should be faster in any game that can stress a 7800GT. You should be able to get a male DVI<->female HDMI adapter, and a male-male HDMI cable, for $15 shipped, or thereabouts, from Monoprice, in case you notice dual DVIs being hard to find. GTS 250 (8800 respin) and 5670 would also be worth looking into, for a bit more gaming performance. However, it will not be likely to affect screen recording much, if at all.