Router drops connection with high activity..help appreciated.

[desar]

I have a DLink DI-514 router and have 4 hard-cables and 1 wireless laptop connected to it. It has been workign fine but about 2 or 3 weeks after I added the 4th computer to the network, the internet connection would drop when I would try to connect to a multiplayer game or use a speak program like Skype. Some suggested problems were that the router was overheating because of so much traffic and it isnt really in the most ventilated area. I tried moving it to abetter area and put a fan on it but it still didnt work. I've seen reviews on this model and noticed that it tends to overheat. People have also suggested that when more than 5 computers are connected to the network, the traffic makes the connections unstable and thus lose connections when I try and use any high-bandwidth programs. Any suggestions/help would be greatly appreciated, its extremely frustrating.
If your savy or have a clue what may be the problem, please reply.