I’ve installed it just the other day and it is fantastic.
Let me say this, I did have trouble with the drivers.  Windows 7 installs everything automatically under windows update, that is IF you have WIFI working, but that was a struggle to begin with.

Windows 7 feels much better than Vista that I’ve tried a while back.  Vista was very sluggish and bogged down my laptop and just wasn’t fun to use.  The 7 on the other hand has minimal requirements and it runs just as well as XP and stays quiet.

I wasn’t able to get every function to work on my ancient laptop, but enough to live with.

What doesn’t work:
Fn + volume controls (though Fn + Brightness, Pg Up, Pg Dn work)
S1 and S2 keys (sony notebook settings wont install and or operate correctly)

Apart from that, everything else seems to be just fine.  Even my port replicator is working.  If you have trouble using XP drivers, try S360 Vista drivers.. they worked for me!

My s170 specs:
2.0 Ghz Mobile M
1GB RAM
60GB HD
ATI 9700 64MB