Here's an update on windows latency
I don't know if anyone else has figured this out, but I only seem to find posts of people giving up.. I managed to get my ( full duplex) audio latency quite low (with perfect quality), running a guitar through with (to me, at least) unnoticable delay (set to 2ms in pd) at 96kHz and 256 sample buffer size..I have no idea what the true latency is though...

I use my interface(M-AUDIO fast track Ultra)'s ASIO driver.
The sound does completely cut out whenever I change any audio settings thougth (in the ASIO menu)-also, my driver disappears from the list, but everything works again the next time I run pd.. So I simply save the settings and restart pd.. This is not much of a hassle to achieve such good results.
I haven't tried midi yet, but I will do so sometime during the next months..

It is quite an iffy system, I know, but my point is: it is possible..