Sorry if this has allready been put up here (but I couldnt find it)...
Anyway I have a Mandrake 10 installed with an (almost) vanilla 2.6.7 kernel and I to suffered from the garbled console problem when I had tv out enabled (gf4 440 - 6106 driver). This was a problem because I really couldnt live without a boot splash screen on my tv, X, the nvidia driver and occasionally console input (via pressing Ctrl-Alt-F1 etc...). So heres what I did to fix it.
Go see spock here
now this guy has got patches for the vesa frame buffer (the thing that the nvidia driver doesnt get along with). So apply what ever patch suits your kernel (2.6.7 for me) follow his instructions and bob's your display driver! Then I just re-ran the boot splash scrips (note: I did not use the gen-splash utilities).
Then it was _almost_ all good.... Fonts not displaying properly.... Well spock the good lad also has a fix for that! Just go to his
and get the miscsplashutils-0.1.2.tar.bz2 or later, un-tar and run make make install on this puppy reboot and your fonts are fixed!
And now Im sitting back switching from console to X to console to X like a pro!
Hope it helps.