You're probably on an ADSL line -- that's what the "A" stands for -- Asynchronous. It means two different speed categories up and down. So you're just like 95% of everybody on the internet.
If you want to test your throughput in a different way, go to the Apple website and DL the Mac OS 9.2.1 update. The file is 82MB long. Time how long it takes then do the math to figure out your average DL speed.
Regarding your UL speed. With most connection types, your UL speed will be much slower than your DL speed.