The rendering system has changed quite a bit since 0.98 (mainly due to speed issues). Most problems now appear to be driver related (Nvidia being the worst culprit followed by Matrox!). It should also be noted that Tattoo is not really going to work properly under less than 24 Bit Desktop bit depth (I have mine set to 32 by default).
That being said, your system specs are almost identical to mine!
That being said, your system specs are almost identical to mine!