Both chipsets are touted as cleanest Svideo/composite capture cards for under $100 ($35-50 mostly) and are Dscaler compatible. The older BT878 chipset works with Dscaler but is noisier on Svideo/composite capture. Some cards come with TV tuners built-in but I recommend using a VCR (JVC SVHS is better than plain VHS due to Svideo output and the more expensive SVHS has Time Base Corrector and better tuners than the cheaper ones--there are other SVHS brands but I favor JVC for its low cost/quality ratio). Built-in tuners generally can't compete with external tuners in VCRs for less electrical noise, channel change responsiveness, HIFI audio, and (S)VHS playback ability.
Some are having good luck with HDTV or hardware compressing capture cards for their Svideo/composite capture.
STB scalers like IscanHD can do wonders but will cost you $1500. Other scalers like Lumagen Vision or Focus Enhancement CS-HD for $1K are very good also. If you want to spend less Zinwell Briteview/AVT-3700/AVT-3800 can offer you decent scaling for $400-500. The HDTV upconverter is pretty good too for $500-600. If you want ultra cheap scalers ($150-200), check out the Viewsonic Nextvision 6 or those that use the Trident DPTV 3DPro chipset (S-media EZV-BOX http://www.coolerexpress.com/sez3dtvpd.html
--same chipset in the Zinwell/AVT series without the component inputs and has VGA output only (no component output like Zinwell/AVT). The Smedia unit probably does not do anamorphic squeeze for anamorphic STB DVD player input, but some PJ can do the squeeze via VGA input (not sure if yours does but for TV or VHS which is nonanamorphic so probably not important). It also may have Macrovision issues but for TV it's again not important. For VHS/DVD this may be a slight problem (very mild light/dark pulsing every 3-4 seconds).
For DVD it's hard to beat HTPC but some have gone for the upconverting DVD players like Momitsu V880 for 1080i/720p via component/VGA/DVI or Zenith DVB318 1080i/720p via component. From my own experience, DVB318 1080i works great with my XGA DLP via component.