DI-514 i have a DI-514 router, with two computers and i recently noticed that my internet speed got slow all of sudden and i tried to download rapidshare and it says im already downloading something with my ip i think somebody's using my router or ip how can i find out? and if so, what can i do to block them? please and thank you!

Do you have any encryption / security on your wireless network? If not, then someone probably is using your connection.
To find out, log onto the router (try address 192.168.1.1 in internet explorer) and have a look at the either the access logs or the addresses given out via DHCP over the wireless LAN. You should get an idea who has been on that way.
Google for setting up a secure wireless network to resolve this.

PLEASE RATE ;] you can find out whos accessing your router by logging into it. Usually 192.168.1.1 once your in there is usually an option for attached devices or connected devices it should show you what computers or devices are connected to that router