Yeah, ATi drivers have been quite poor in the past, and to a degree still are under the Linux, but they are getting better there as well (and in contrast to nVidia, they released sourcecode to let the community make opensourced drivers :D ). But since like already the HD3000 series their drivers have become just as stable and good as nVidia's to be honest. I've been hopping from nVidia to ATi and vice versa if one would give me better performance, etc. Thank god for standards, so no.. your nVidia chipset shouldn't make any difference with putting an ATi card in it (I would even call it hilarious irony ;p ). p.s. Macs are nice machines, but their price/performance ratio is quite poor. If I had the cash, I wouldn't mind getting a Power Mac, replace the videocard and put Windows on it :p