Personally I’d go for 8.04. 8.04 is getting a bit old but it’s very stable. I think it’s something to do with it being a so called “Long Term Support” release. I’ve had CUDA version 2.0 ,1 and 2 working on 8.04 with no problems. CUDA also works fine on my current 64-bit 8.10 set-up although 8.10 itself kinda gets on my nerves…
8.04 LTS support has been dropped in CUDA 2.3 and the important “out of the box” toolchain and key libraries (like boost, for example) are now out of date enough to cause difficulties with useful CUDA tools. cuda-gdb isn’t supported on anything earlier than 8.10 and Ocelot won’t build on a stock 8.04 LTS install, for example.
I would recommend 9.04. It has been working flawlessly with CUDA 2.3 on my development machine for a while now, and I am yet to find a serious fault. Cuda 2.2 will also work without modification under 9.04.