I've been lurking here for over a year and this site is a great information resource. I have been researching building a HTPC/DVR and need some help.

main goal-timeshift OTA HD

proposed setup:
hitachi crt hdtv monitor,only has component inputs, no HDMI(already have).
sony str-de995 reciever(already have)
dlink dsm520, netgear eva8000 or similar multimedia streamer
hdhomerun networked tuner or mdp-130 hd tuner in pc
NAS or large usb external hard drive for storing recordings
current pc:tekram s381m mobo, 950mhz celeron, 100mhz FSB, 512 RAM, onboard video/ac97 audio.
may also add mediamvp sd streamers to non-hd tvs
networking through netgear router and cat5 ethernet

the key questions are:
is this pc adequate to run dvr functions and stream hd to dsm520?
what ATSC tuners will work with this old processor besides the mdp-130?

thanks in advance.