Tried to boot the LiveCD and F10 doesn't seem to like my Radeon X300SE.
Got this in Xorg.0.log (full log attached).

Backtrace:
0: /usr/bin/Xorg(xf86SigHandler+0x79) [0x80bc5d9]
1: [0x132400]
2: /usr/lib/xorg/modules/drivers//radeon_drv.so [0x76f04b]
3: /usr/lib/xorg/modules/drivers//radeon_drv.so [0x76fb8f]
4: /usr/bin/Xorg(xf86SetDesiredModes+0x1af) [0x80e585f]
5: /usr/lib/xorg/modules/drivers//radeon_drv.so(RADEONScreenInit+0x1b20) [0x72e$6: /usr/bin/Xorg(AddScreen+0x19f) [0x806ad2f]
7: /usr/bin/Xorg(InitOutput+0x206) [0x80a3b66]
8: /usr/bin/Xorg(main+0x279) [0x806b4c9]
9: /lib/libc.so.6(__libc_start_main+0xe5) [0x42e6e5]
10: /usr/bin/Xorg [0x806aab1]

lspci -vvv

05:00.1 Display controller: ATI Technologies Inc RV370 [Radeon X300SE]
        Subsystem: PC Partner Limited Device 0631
        Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Ste$        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort-$        Region 0: Memory at fe2e0000 (32-bit, non-prefetchable) [disabled] [siz$        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3ho$                Status: D0 PME-Enable- DSel=0 DScale=0 PME-
        Capabilities: [58] Express (v1) Endpoint, MSI 00
                DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <128ns, $                        ExtTag- AttnBtn- AttnInd- PwrInd- RBE- FLReset-
                DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupport$                        RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                        MaxPayload 128 bytes, MaxReadReq 128 bytes
                DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransP$                LnkCap: Port #0, Speed 2.5GT/s, Width x16, ASPM L0s L1, Latency$                        ClockPM- Suprise- LLActRep- BwNot-
                LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- Retrain- CommClk-
                        ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
                LnkSta: Speed 2.5GT/s, Width x16, TrErr- Train- SlotClk+ DLActi$

From dmesg, probably related (full dmesg output attached)

[drm:drm_buffer_object_validate] *ERROR* Failed moving buffer.
[drm:drm_buffer_object_validate] *ERROR* Out of aperture space or DRM memoryquo$mtrr: base(0xfd514000) is not aligned on a size(0x7e9000) boundary
[drm:drm_mode_getfb] *ERROR* invalid framebuffer id