Vista MCE How many digital tuners?

I've read a few threads and I would like to have 3 digital tuners(clear QAM) and 1 analog working under Vista Media Center, is it possible? I'm currently using the HDHR and it has no problem with the dual tuners. If I'm limited to two digital in MCE, I assume I could use a standalone tuner such as OnAir Creator/GT and use it's own software to record analog and digital with it in addition to MCE recording with the HDHR device.

Are there any plugins that will play ts stream files in MCE that will allow fast forward/skip and/or rewind functions using the remote control? I've got MCE playing ts files, but I have no real control over them other than pause and stop.

Any thoughts on the subject?

Thanks, I'll give it a go, unfortunately my motherboard is out for replacement, but if I can get the tuners to all work in MCE, then the ts streams problem won't be an issue, since I'll be recording everything in dvrms anyway.