I've been looking at lg3d in my spare time lately, and I'm trying to figure out whether or not running it on my Radeon 9800 will work.
I've seen advice which says that DRI will work, fglrx won't. I don't think that I have a whole lot of problems with this on the face of it, since compiling ATI's kernel modules ranks slightly higher on my list of enjoyable things to do than eating a bowl of worms...
but my question is, what is DRI? Is it a universal set of drivers somehow, or if not, what exactly is it an alternative to? Their own website's no help, partially because I'm looking for an answer in just this specific context.

Thanks!

As for whats the differance,Im not fully sure.
Other than the fglrx is Proprietary and DRI is open source.
But i do know fglrx works with my ati 9800 SE card just fine.

:~$infobash -v
Host/Kernel/OS "Kanotix" running Linux 2.6.13-kanotix-2-iron i686 [ ]
CPU Info AMD Athlon XP 3200+ clocked at [ 2205.232 MHz ]
Videocard ATI R350 AH [Radeon 9800] X.Org 6.8.2 [ 1280x1024 @75hz ]
Processes 109 | Uptime 2days | Memory 995.301/1009.56MB | HDD Size 392GB (2%used) | GLX Renderer RADEON 9800 SE Generic | GLX Version 1.3.5272 (X4.3.0-8.16.20) | Client Shell | Infobash v2.50rc4
:~$ xdpyinfo | grep dimensions
dimensions: 1280x1024 pixels (382x313 millimeters)
:~$ lsmod | grep fglrx
fglrx 257576 7
agpgart 28616 2 fglrx,nvidia_agp
:~$glxinfo
name of display: :0.0
display: :0 screen: 0
direct rendering: Yes


Direct Rendering Infrastructure (DRI)

One of the problems with Direct Rendering is that other applications (say the X11 server, or other OpenGL clients) might want to talk to the hardware at the same time. In addition there can be problems with security, multiple users, and several other things caused by the complexity of Unix. An intricate software design called the Direct Rendering Infrastructure coordinates everything and prevents problems. The DRI used on Linux was designed and implemented by Precision Insight (who were recently bought by VA Software, former VA Linux). The DRI was integrated into XFree86 4.0 and is available in that and all subsequent releases; current development is concentrating on Xorg instead of XFree86.


Mesa

Brian Paul wrote a free open-source implementation of OpenGL called Mesa. The name has no hidden meaning, it just sounds nice. The original versions of Mesa only did software rendering. Recent versions of Mesa have had accelerated backends for Glide, DRI, etc.

The Mesa website is at [WWW]http://www.mesa3d.org/.

Oh, I know....it's working fine with my card as well (or was, until Windows required a reinstall and wiped my hard drive in the process - long story...(I hate Windows)). But apparently fglrx doesn't play nicely with Looking Glass, whereas DRI does... so I was wondering whether they were completely interchangable, or if I had to install part of ATI's drivers, and then install DRI on top of them, or something odd like that.

But from what you say and what DRI's website says, I can pretty much can the proprietary drivers. Which, if so, makes me incredibly happy

Yes,correct...they install all by themselves and leave you the pleasure of "canning" the other.

have a look-see;
http://dri.freedesktop.org/wiki/Building