Unfortunately, 10.4.1 is extremely finicky regarding the supported hardware: the Intel GMA900 and GMA950 chips are effectively the only GPUs supported with graphics acceleration.
It's also important to point out that 10.4.1 doesn't support the final revision of the Intel binary format that eventually shipped with the first Intel Macs back in 2006: it's got a custom binary format that is specific to 10.4.1 and 10.4.2, so no modern program (even if 10.4 compatible) will run on it, with the exception of PowerPC binaries which should be correctly translated via Rosetta. The only Intel software that can run on 10.4.1 is the software that Apple provided bundled with OS X (and very early versions of Xcode for Intel).
On a side note, if you do choose to install a more recent version of OS X on a different partition, you should be able to install 10.4.3 (which is still a developer release) without problems: that version is recent enough so that it should be capable of running real programs and also has a better hardware support, notably for ATI graphic cards (nothing fancy, though, you're pretty much stuck with ATI Radeon 9600 and similar devices). You can have a better picture of what's supported on both systems
here and
here. Note that these lists were compiled with hacked versions of OS X in mind, but since the Apple DTK uses a customized version of an otherwise standard BIOS (and not Apple EFI like all the Intel Macs that shipped later) I see no reason why these graphic cards shouldn't be supported out of the box.