First, a quick disclaimer of sorts, I've only been using Linux now for a little under 2 weeks and I'm not exactly sure what the linked changes did exactly, all I know is they worked perfectly for me.
I setup a Mythbuntu 8.04 box with a nVidia GeForce4 mx 440 not long ago, suspend was a must, resume would however leave me with a black screen and the need to do a hard boot, I tried countless things none of which worked, until this link,
http://blog.vaxius.net/?p=43
Hopefully this helps someone like it did me.