Sorry Loadamoney I've got to disagree with you on that (ish).
If you have a 1800xt currently on a 1280x1024 video card I agree and see no point in upgrading to another current gen card, the increase you'll see will be negligable. If you have plans to move to a bigger screen at some point then the increase you'd get by going to a 1900 (for example) would help more. If we're to believe the statements from MS, ATI and Nvidia then you would get an ever bigger increase with the next gen cards, plus advantage of DX10 support.
DX10 cards are not just attractive to people with low end cards, they are attractive to people playing games etc on 24" monitors that want to be able to play with the detail right up and full HDR/AA/AF etc.
The next gen cards (and lets ignore the DX10 bit for a second) are supposed (alledgedly

) to be "substantialy" faster than current gen cards, even leaving the relative merits of if anything will take full advantage of DX10 aside.
Of course if you already have something like a 1900 or a 7950 then there wouldn't be much point unless there was a specific program/game that appeared that required DX10 to play. I can't think of any at the moment, even Crysis will play on DX9 albeit without the DX10 bells and whistles.
The argument is the same as every time a new gen of video cards appears. Having said that the addition of wanting to play at 1900x1200 with everything maxxed and DX10 could make the next gen cards more attractive on day 1 than in the past.
In the end if you can justify buying a 7950 or 1900 for better performance then you can almost certainly justify waiting a few weeks for the next gen cards to appear, unless, as i said you are on a budget or not planning on using a >20" screen any time soon.