nVidia cards are generally a fine choice for use with Linux. There are many who would complain that the proprietary nature of the closed-source video driver is a handicap, but in practice nVidia has been very, very good about maintaining support for all their cards with minimal user effort required.
nVidia Chipset Feature Matrix
Note that nVidia makes the chips that drive the cards, but it is the choice of the OEMs (original equipment manufacturers) as to specifically which outputs a given card will have. The outputs listed in the chart represent the type of outputs typically found on a given product line. Don't order something blindly based on this chart if you need a specific output because these can differ from model to model.
The 7xxx series were the last models nVidia included support for X-Video Motion Compensation ( for MPEG-2 video) acceleration through the hardware. The 6xxx series of cards have the first chips nVidia has made which feature support for PureVideo (a more broadly-applicable form of accelleration which can be used for h.264 decoding in addition to MPEG-2) but unfortunately the nVidia proprietary driver does not support this at the present time. The 7xxx and higher models appear to be PCI Express x16 only.
The chart below only lists native video outputs. Note that most DVI outputs can be converted to HDMI with a reasonably inexpensive adapter.
|Number||Core Type||Available Forms||XvMC||PureVideo||Composite||S-Video||Component||VGA||DVI||HDMI|
|6200||NV44||PCI, AGP, PCIe||Yes||Not under Linux||Yes||Yes||No||Yes||Yes||No|
|6600||NV43||PCI, AGP||Yes||Not under Linux||No||Yes||Yes||Yes||Yes||No|
|7050 PV||NV44||Integrated||Yes||Not under Linux||No||No||No||Yes||Yes||No|
|7200||G72||Integrated, PCIe||Yes||Not under Linux||No||Yes||Yes||Yes||Yes||No|
|8600||G84||PCI Express||No||Not under Linux||No||Yes||Yes||Yes||Yes||No|
- Note: The above list is not a complete list by any means, and lacks mention of the oldest cards (MX440 and so forth) which makes the composite video output column somewhat useless. The main utility being that for the composite-output-only cards, a different 'nvtv' driver is usually needed. nVidia's "standard" driver will work fine for all manner of TV output with all cards newer than those.