Get a block from
OverclockedPC for your Radeon 9700, and you wont have to worry about the shim; the block is adapted to fit it.
Don't bother with a GeforceFX. Comparative testing at PCPro.co.uk has found it to be
slower than the Radeon 9700 except for one benchmark (the 3D "Nature" test) where it was only 7% faster. Take into account the 30% price difference and the fact that the GeforceFX is pretty noisy (I mean, just
look at that fan setup! That thing just begs to be WC) that pretty much clinches the deal for me...