The DX vs OGL thing has already been discussed over and over... I agree with One Eyed Jack, probably that 'software layer' isn't so complex that it'll make run at half fps, but just some fps drop.
One thing I'm sure of is I won't upgrade my machine just because of Vista. I can't stick to one MS OS only because there are lots of different things I do with my pc, and no single OS fits all perfectly. Currently I use W98, W2K and WXP and about to install linux again (all in the same pc). Maybe Vista will find its space in my hard disk, maybe not :)
One thing I'm sure of is I won't upgrade my machine just because of Vista. I can't stick to one MS OS only because there are lots of different things I do with my pc, and no single OS fits all perfectly. Currently I use W98, W2K and WXP and about to install linux again (all in the same pc). Maybe Vista will find its space in my hard disk, maybe not :)