I've been using both VB and even AutoIt, from/on a PC (XP and Vista). I should note that I also compiled and ran the sample SDK program related to ECP (it uses HTTP 1.0). One thing I noticed with it was that where it does a get/apps the response contains no apps. It gets the header part of the repsonse message back fine, and shows an appropriate number of bytes that should be in the message body. But there is no message body (ie. there's the header , but no data).
A strange thing is that I had not been using the additional header in POSTs (or GETs). Keypress seemed to work without it. Get/apps had random problems, sometimes there'd be a usable response - sometimes not. But when I got to trying to launch apps nothing worked until I added the additional HOST: header. Now I've gone back and added the header to eveything I do (except the SSDP Discovery of course). That's seems to have produced reliable exchanges.