Take a look at the Advent Vega. It's being sold by PC World/Dixons/Currys.
£250 or so, runs Android 2.2, has a NVidia Tegra 2 chip in it.
Only downside is no 3g, but that doesn't really matter if you have a mobile phone that can act as a hot spot.
I've borrowed one from a mate at work for a couple of days, it's pretty damn slick, benchmarking reckons its about 10-15% faster than my Nexus One running a custom 2.2 build.
It's got a full size USB port on it, with the custom software pack that's available at Modaco you can make the USB port act as a host port and use memory sticks in them, GPS dongles have been found to work as well, I dunno if anyone has tried using a USB 3g modem on it though.
Takes microSD cards for memory storage has an HDMI port on it for playing stuff on your TV (Angry Birds on a 46" screen is pretty good).
Plays most non-MKV formats from my XBMC box via upnp more than happily.