There is also the "throw money at it" fix for this – an SSD. I've been enjoying one, of the Intel X25-M G2 variety, it solves VM paging/thrashing slowness very nicely and is hella fast to boot.
I have the same drive. I currently have 6GB of VM, but I've had it up as far as 14GB with no issues.
I've actually had Photoshop run out of the 20 GB that are free, by allocating all of it to manipulate a huge image. It takes about two seconds for it to allocate all of that space.