Laptop Randomly Disconnecting from the internet?

[Grigsbay]

My laptop randomly says unable to connect even though the network connection is good and there seems to be no visible reason as to why it would disconnect. I have to restart my comp in order for the connection to work again if anyone has any insight I would appreciate it. Oh and I have tried both Firefox and IE 7 the same problem happens with both. My computer is a gateway model m-6816 and i use vista so any help would be greatly appreciated thank you!
Oh I forgot to mention it does this when I am connected directly to the internet not just through wireless, and I have used several different routers

and I have had a few different internet providers do to the fact that I am in the military and move around a lot

[sector182]

you need to move closer to that little antenna thing.

[whazaw]

may be it's your router, my be buy another wireless card