I have heard of people having trouble with Netgear routers and Mac's, but this problem grabbed my attention.
However, you are saying that you CAN get a connection, BUT you have to have the PC on? Sounds like your connection is running THROUGH your PC. Either your router is not set-up right or your Mac is configured to connect to the wireless card on the PC and not directly to the router. If you can plug your Mac into the router and have it work flawlessly, then you know the router can handle the Mac and the problem is strictly wireless. If the problem is strictly wireless, it can be either the router settings or your mac's settings that are wrong. Basically, if you need the PC on to connect to the router, your doing something wrong. Turn the PC off and use your Mac to search for wireless networks in range.
I have a Lynksis router with Tomato Firmware that is directing traffic to an iPhone, 3 wireless XP laptops, a wired desktop xp pc and a XBox 360. I have to run WEP since one of the laptops just doesnt respond to WPA (I have no clue why, but where I live is rural enough it isnt a big deal).
For starters, answer these questions. And please turn the PC off for this part.
1. Did you rename your network so it doesnt just show up Netgear or Lynksis? (yes or no will do)
2. What level of encryption (if any) do you use? (WPA, WEP, Open access)
3. What devices use this WiFi network? (Phones, laptops and what OS's you use)
4. When you search for networks on you Mac, how many networks come up and are they locked? (Some Windows laptops try to act as access points if set-up incorrectly, but this usually results in no internet at all, I want you to search for networks when the PC is not on)
5. Can you plug your Mac into the router and if so, will it work quickly when plugged in?
We need to narrow down possible issues. If the Mac works fine plugged in, then at least we know the router can work with Mac and that the issue is strictly wireless.