Macbook Pro wifi doing odd things...

Hi all,

I have a Macbook Pro 2009 (I forget if it's early or late), and, as much as I love it, the wifi has been playing up a lot lately. For a while now, I'll find that the wifi connection will just stop working. It'll still show it's connected, so I won't get an error message on my browser, but nothing will load. It's quite a simple fix; just turn the wifi off and on again and it works fine. It's just rather annoying. That's been happening for around a year or just under. Recently though, I've found a new problem. The problem that I mentioned above will happen (things will stop loading even though it thinks it's still connected to wifi), so I try restarting the wifi as normal. I find though, that once I turn it off, it sort of freezes, and I can't turn it back on again for anything, even if I go into system preferences to do it, it usually thinks it's still one while the top bar thinks it's off. The only way I've found to rectofy this is to restart my computer. Then it's fine, but when this happens every few days, it starts getting infuriating. I'm on Mountain Lion 10.8.5 and know the wifi isn't a problem as it's fine on my iPhone 4S. Could this be problem with speed? I have 4gb RAM but only a 160gb HD with only about 20gb free. Thanks a lot!!