You have to think though, DX10 is not going to be worth having for about a year or so from now, possibly longer as DX10 games won't be flooding out, when it hits theres gona be Vista (obviously), and Crysis, and there may be something else is it really worth lashing out £400 or whatever for an OS, and the odd game which will run fine in DX9 anyway, advantage of getting the x1950 is that you can miss out the R600/G80 and get a faster, better DX10 card further down the line when theres actually something using it, and its worth having, by which time R600/G80 will have been well passed.
If you have a high end card now then you can miss R600/G80 out as your card has donkeys left yet, id only go for R600/G80 if you wanted the fastest DX9 card around, and your card could'nt handle DX9 games fine anyway, be worth it for those users with low end cards, but high end cards are going to run everything for a while yet.
If you have a 9700pro, and its still doing fine for you, then yeah miss the x1950, and wait for the R600, but thats around Vista time which is around Jan/Feb, depends if you can hang on that long and wether your 9700pro will still be doing you fine till then, i certainly would'nt put off getting a new card just because DX10 is due as as i said, by the time its being used more, worth having your probably talking about a year odd from now, and everyone knows a year is a long time in graphics cards, loads will have come and gone.
I don't get why ppl are saying im not getting x1950 etc... as theres no point not with DX10 cards coming out, when DX10 cards come out it does not mean the x1950 etc... is suddenly not going to work anymore, run everything as a slideshow etc.... as they will be perfectly fine long after the R600/G80 comes out, they will still work, they will still cut it, so just get one and miss out R600/G80 and get a DX10 card when its being used etc... as x1950 etc... will easily last till then.