@Sam: Though it's a little rare, there are times where Xvesa doesn't like a particular video card or other piece of hardware needed just to start the GUI. Depending on which ISO you've downloaded, there are simplistic ways to find out which flavor might work best for you.
My recommendation would be to download CORE (instead of Tiny or Plus) which is nothing more than the basics to get you into CLI.
From here, let's use just the Core CD to boot the machine in question.
At the command line, enter the following:
tce-load -wi Xvesa Xprogs flwm_topside wbar
If there are no problems shown while downloading, type in
startx to launch the desktop (X server) and wait.
* If there's a hardware problem Vesa can't handle... it'll usually complain. Stop back here and give details.
If this doesn't bode well, you might want to try a more powerful (feature-wise) server, such as Xorg. Reboot back into the clean CLI and:
tce-load -wi Xorg-7.6 Xprogs Xlibs flwm_topside wbar
Again, if no problems, launch
startx and sit tight.
* Xorg is more likely to complain about video drivers. We WANT to know this information so we know which direction to take.
If Xorg can't handle video on its own, then type in
tce-ab
and do a search for the word firmware - specifically looking for brands you might have in your machine. For example, let's say you have a Raedon based video card (such as ATI, AMD, etc.) you'll want/need to install the firmware-raedon extension so Xorg knows how to communicate with your video hardware. This is a short list and not necessarily based on video cards. If you don't find your blend of video cards, repeat the search using the word "graphics" and finally the larger list searching for "xf86" (looking for files starting with xf86-video-brand.) If you know in advance what video hardware you're using that would be helpful skipping past most of the hunting.
If all else fails, we'll keep digging!
Good luck!