I have a fujitsu U820/U2010 which has a similar sized screen but is very chunky; however, if I could detach the screen it'd be a perfect tablet for me. shame that rollup or foldable screens have eluded us.

The screen is ultra hi-res (1200x800) - so much so that I had to tweak screen fonts etc to make things easy to read! 1024x600 in a 5" screen is plenty.

I don't actually make many voice calls and I'd be happy to use a wired or better a bluetooth headset most of the time; when I used my n800 for voip it was fine to use speakerphone or just a headphone and its built-in mic. I suspect if I had the Streak I would get a £20 almost disposable 2G-only nokia phone (these often have excellent battery life) for voice calls and treat the phone part of the streak as a data device and emergency-only voice calls.