Slow Qwest DSL downloads

I have Windows Home Vista Premium and am using Qwest DSL for my Internet
Service. I have always experienced buffering on news videos and You Tube. I
thought it was just an unfortunate choice of ISP. However I noticed that the
download that I did the other day was only downloading at 25kbs instead of
the 256 kbs that Qwest claims. I contacted Qwest, they state that their end
is functioning as it should. I contacted HP and they state that I need to
reinstall Windows Vista. My question, Is that truly necessary, and most
importantly, is it really going to help? Is there anything else I should try
first to get the 256 kbs service that I have been paying for for 8 months and
not getting.