Start, Run, type" cmd.exe " (without ""), it will open a window that looks like msdos, Type "ipconfig/ flushdns" (without quotes), press enter, then type "ipconfig/ release", press enter, then type "ipconfig/ renew" and press enter. Close the cmd window and your connection should improve slightly.
More info about your isp (internet service provider), and your type of internet connection ie. wireless, cable modem, etc. would be helpful to diagnose your specific issue. The recent hurricane chain may have something to do with it as well, Ike has been messing with the wireless transmitters in my area (Central TX).