Well, if you can't reach 90% of your ISP's advertised speed you might have a problem.
Luckily that problem can be fixed in most cases by tweaking your windows registry.
There are a lot of tweak programs out on the internet. Unfortunately, not all of them do the job right.
When you need help with tweaking, add these things in your post.
1. What OS are you running? Examples: Windows 98, Windows XP. If you have XP make sure you have SP2 installed! Also download the p2p fix for S