I've been running lucid for a few days, and I think quality control has significantly slipped in Ubuntu. Yes they are only betas, but with only 2 weeks left before release, I have seen lots of bugs still remaining. Within a couple days I found that screen-saver crashes often, several apps can't properly auto-disable PulseAudio anymore and don't work without hacks, PHP 5.3.2 segfaults, themes didn't install fully on upgrade, and (of course) the memory leak which results in Lucid using up all the RAM in my system (yes I've submitted bugs (or found previously submitted tickets) on most of these already). Other things like Wine segfaults seem to be resolved by reinstalling, but overall this upgrade has not gone smoothly for me. I've been, overall, happy with (X)Ubuntu over the years, and like the 6 month cadence, but, in my opinion, they should really focus more on quality for their LTS release. I certainly wouldn't recommend an upgrade to 10.04 in its current state, though I plan to stick with Ubuntu personally. Generally, I consider Ubuntu to be a more user-friendly and more current Debian, which I like, but I guess I should learn not to be an early adopter if I care about stability.

I love MythTv, and have been using it for years and years, but it is absolutely not easy (though I have more obscure hardware, and have never used mythbuntu). I've also tried being a sysadmin for my friends' myth boxes....I would never wish that on anyone. The stability has always been the biggest issue. Random crashes are extroadinarily annoying. With Firewire, I found recording very unreliable, image quality is very dependant on the capture method. But I haven't seem anything that can support my High-Def recording with auto-commercial detection, and for that,I'm willing to stick with it.

I've heard that you can run 'Play On!' in a virtual-machine on windows to convert netflix to upnp streams (which can then be watched on Linux). I haven't tried it myself though. Certainly not ideal, but perhaps viable for those certain use models.

Also Blu-Ray is still really hard in Linux. I've considered a Windows MythTV frontend with a linux backend which might give me the flexibility I want, but I don't think there's a good integrated solution for that.

According to a-v comparatives:
http://www.av-comparatives.org/comparativesreviews/corporate-reviews

Microsoft's AV software is very good. It has low false-positives and generally scored quite well. If the same capability is free, I don't see a reason not to recommend its use. I certainly don't work for a-v comparatives, but they were around before Microsoft was in AV business, and their top rated software changes pretty freqeuntly. I'd call them reasonably unbiased, but judge for yourself.