Hi Chris, thanks for your response

Well, color definition is important since the project i am working on
involves color tracking (two mallets one blue one red), so some
resolution is necessary to achieve that. they are between 1.5 and 2.5
meters away from the camera. the camera i have been using is a 3ccd
canon 1080p30, but i am digitizing the svideo output to 320x240 for
the actual tracking.

With resolution that low you could switch to an interlaced DV camera and use 60 720x240 fields per second. Certain capture cards under directShow will do this.

so i think i am looking for at least 720p60.

JVC makes HDV cams that run at that but I don't know if the cheaper 'prosumer' ones do it. Panasonic P2 camera does that I believe and that camera is just over $5k.

so... what are the lowcost 1080p60 cameras you mention? how good is
their color resolution?

Oh they aren't low cost. The lowest cost one is about $30k and increase from there. Most of these aren't video cameras but 'digital film' cameras so their resolutions are more like 2048x1536 (which SDI_HD supports). These are all bleeding edge and quite rare.

About PCI cards, i'll check AJA and BlackMagic, I think i'll have to
stick with them since so far they are the ones with least latency and
your comment confirms my experience. I was using a pinnacle card and a
hauppauge card, do you know these? do you know if AJA and blackmagic
are better?? these two are old cards so i suppose more recent ones
should be faster...

AJA and BlackMagic are professional capture cards and they are not that cheap. The standard resolution cards are almost $1kUSD and the HD ones are over that amount. The HD ones have a bit more latency.

Have you tried turtle beach??

No.

http://www.turtlebeach.com/products/vausb/home.aspx

this is the only external card i found with low latency, but didn't
get to measure precisely how much difference this had compared to the
PCI cards.