tap F8 and select last known good config and se if that helps. if not then try safe mode as above and if it all starts up ok then its more than likely software loading with windows thats the problem. try clicking 'start/run' then type 'msconfig/startup' make a note of everything listed here and untick everything apart from your AV and firewal and restart again. does it work ok now? if so go back to msconfig and put one tick back at a time and restart untill it hangs then you have found the problem maybe.
also see click here and work your way through it maybe.