I've lost count of the number of Linux distros I've tried and rejected because of:
1) Ugliness (especially screen font-rendering)
2) Device problems, mainly wireless networking
3) Video driver problems, e.g. machine locks up when Compiz or similar enabled.
4) No support (or broken support) for power management, hibernation etc.
5) All of the above.
Even recent 'big-name' distros like OpenSuse and Fedora have had one or more of these problems, at least for me, on my Acer laptop.
Finally I believe I have found a Linux distro I believe I really, honestly may be able to use as a Windows replacement. It's LinuxMint 5.
I am very sensitive to (or intolerant of) poor font rendering on laptop displays. This has been the stumbling block for all previous distros, even those with support for anti-aliasing and font-hinting. Finally, the LinuxMint distro team appears to have sorted this out: the fonts render beautifully.
All the other issues in my list are addressed: the system picked up my wireless network immediately and connected as soon as I entered the pass-phrase. As far as I can tell, all devices appear to work, and the power-management stuff works.
Finally, for me the aesthetics are spot-on. The default theme and the choice of colours really works for me. This matters, when you're spending significant tim in front of the system.
This is a truly excellent distro - far and away the best I have ever used. This one will stay on my laptop and I plan to make the effort to use it instead of Windows.