Just installed TT7 on an i900, so I don't know if it would be the same. Got the "Poor GPS signal" each time, even though Garmin XT would get a lock in about 5-10 secs.
As blackmeto mentioned, I tried GPSgate to see if this would work, and hey presto, lock very quickly. You can get a trial at
http://gpsgate.com/index.php?id=7. Word of warning though, any GPS portsplitter programs like GPSgate will chew the battery no end, so make sure you've got the phone on charge when you're using TT7.