For S-Video/component i am quite happy with the quality/price i got with this
Got mine for $25 on ebay.com
If you want to use hi-res i can't give a model tested first hand. What i can tell you is that:
NOTE: 1. The HDMI input is not intended for use
with personal computers.
2. Only DTV formats such as 1080p, 1080i, 720p,
480i and 480p are available for HDMI input.
The not intended for use with computer should mean that you can't use another audio channel, meaning the adaptor need to be able to inject audio in the HDMI 1.3 standard. (that is less a problem if you have an audio receiver).
I found one here:
on the low end price.
If you want a more featured one:
Note that this is the kind of stuff that can vary 30-40% from 1 online store to another, so it's worth shopping a bit.
On a last note, i would say that it's OK to use it for dynamic use on the TV, but static picture from the computer can "burn-in" over time, so only use that for gaming and watching movie.