Will CPU work in motherboard?

I just bought a Q8400 quad core CPU (upgraded from an E6750 dual-core which I was unimpressed with).

I run an Asus P5N-E SLI motherboard which I got 11/07 and updated the bios on only once (in november because it was unstable) so my most recent bios is an 07 bios.

I heard from several that you don't usually need to update bios before installing new CPU.

So I installed new CPU, turned on system, and it hangs on the "title screen" per say, it says "CPU Processor Speed 2.66 ghz" but doesnt give the name or anything.

Switching back to old processor (back in now), I suspect I need bios update

I go to ASUS website and it shows the list of processors the board supports, but the Q8xxx series isnt on the list. However I still havent updated bios past the 2007 bios. Would updating bios to something more recent allow my new Q8400 to work? Or am I SOL with this processor and have to wait until ASUS gets an update that supports it (if they ever do, otherwise, new motherboard?) Should I use the effort to flash a more recent bios and try the Q8400 processor again?

If Asus haven't yet released a BIOS that supports the Q8400, then you shouldn't put too much hope in having it supported in the future. You lose nothing flashing the latest BIOS. Didn't you check the list of supported CPUs before buying it?