high speed dsl question

Hi, for the last couple of days I have noticed that internet videos keep buffering. I just did a speed test of my internet connection and the results were: upload speed 494 kbps and download speed 490 kbps. I'm supposed to have 1.5 mbps. this seems slow and is likely the reason for the buffering videos I think. what is the most likely cause of the sudden slowdown since it was working great 2 days ago? Is it the modem or a computer motherboard or memory problem? thanks

 

it's working ok now:confused all I did was remove the nvidia video drivers and install them again. first I installed the latest version 182 but was not happy with the fact that there was no icon to click in the tool tray so I removed them. then I installed the version I had been using 169 and for some weird reason everything is back to normal. I can't explain it but all the internet video is playing smoothly. maybe someone can explain it

 

I just did a internet speed test and got 1477 kbps download and 470 kpbs upload. does that seem right for a 1.5 dsl?