I haven't installed Mandrake on the I-Opener, but I have recently performed a Mandrake 8.1 installation on a Toshiba Satellite 1805-S203, which uses a Trident-Acer Cyberblade-Aladdin i1 (this is a Slot-1 chipset that is similar to the Socket-7 Cyberblade i7 in the I-Opener. The system logic differs, but the graphics cores are similar, if not identical).
The default installation of Mandrake selected Xfree86 3.3.6 and XF86_FBDev (the frame buffer X Server), and it worked, but without any acceleration. I then manually ran Xconfigurator and chose Trident Cyberblade (generic), and it works now with XF86_SVGA. However, I must note that there is not much improvement in 2-D acceleration, although the XF86_SVGA server claims to be using XAA.
Ironically, my ancient HP Omnibook 800Cs, with a Neomagic NM2070 graphics accelerator and a classic Pentium/100 easily beats the crap out of the Toshiba Satellite 1805, with its 800 Mhz Coppermine Celeron-II CPU and Cyberblade accelerator, running XFree86. I estimate that the NM2070 outperforms the Cyberblade on 2D window redraws under X by a factor of 10..100.
I'd have to say that those Omnibook 800cs/ct units on Ebay for $200-$300 are great for Linux/X.