HW: Yeah, it looks much better for linux. It seems to have a Transmeta Crusoe plus Ati Rage XC 8mb graphics.
The Transmetas are much, much better on linux; to my surprise, they have no proper power management under windows (!). Yet under linux they scale frequencies just fine.
On the Ati Rage, GL 1.2 and IIRC XV till 1024x1024. But it's a mach64, and the whole kernel part for it has been removed some years ago - so no accel in X, opengl, or xv video. You could try to hunt it down and see if it compiles still though.
You do have one possibility, one of the Mplayer builds with (x)vidix. I think vidix accel did not need DRM, and it worked great when I last tried on a mach64 card.
Vidix output requires root powers.
Grub issue: When in grub shell (press c from the menu), try to tab-complete both the root drive and then check the files are there, ie
root (hd, # tab, choose right one, enter
cat /boot/ # tab, just to see if files are there, don't cat them