WTF?!?!
Speedtest uses your connection to monitor your downstream and upstream bandwidth and see what your connection is capable of. If I connect to a host or set of hosts that can max out my downstream then I'll see the speed within +/- 5% of what the speedtest results were, assuming my ISP provides high QoS.
Where you're confused is how some programs display your transfer speed versus what speedtest is displaying as your transfer speed. They show speed in bits whereas I.E. and other apps tend to show your rates in bytes. 8 bits in 1 byte so an 8 Megabit connection could basically be capable of 8 Megabit/s transfers or 1 Megabyte/s transfers. Same thing.
software programs display speed in bytes, not bits so to get your actual MAX speeds you need to divide by 8.
i ran a test on mine to try to make it more clear
ok so 4889 down, 366 up
so if you divide by 8 i get about 611 down, 45 up
when using say...bittorrent those are the max speeds i will see when using my client
all i am saying is dont run speedtest and see 4800 bits and then try to download something from the web and expect to see that number. although you are getting 4800 bits your max is still gonna be 600 bytes and that is what your download client is going to display