I suggest you might try several things:
1) Move the router around a little. The signal strengh at your wireless PC is affected by the path the signal has to take, how many walls, mirrors, etc, it has to go through, so moving the router a little bit might help. Try moving it both horizontally and vertically.
2) Try moving the antenna. I have mine vertical, but you can rotate it to horizontal or anywhere in between. With your PC above the router, horizontal might just work better
3) Try using a different channel, especially if there are other networks in your neighborhood. From looking at my Actiontec router, it appears that the default channel setting is Automatic, but you can change it to any channel you want, 1 to 11 (Wireless Settings ==> Basic Security Settings ==> 3.Channel). It might take some experimentation, but what you want is a channel that is not in use by other networks nearby. Some wireless cards/notebooks offer a function that allows you to see what other networks are available, and what channel each is using (including your network). If yours has that capability it might help you figure out another channel to use.
Beyond the above, another thing you could try is to buy a higher gain antenna for the router or the wireless client, but that costs money. Or invest in a wireless access point, which can be placed nearer to the computer with signal strengh problems - money again.
I suggest you try the free things first. And maybe someone else will come along with additional suggestions.
Unfortunately, wirelss can be somewhat hit or miss. I presume you are using the Actiontec router that Verizon gave you; some people report that the wireless capability of that router is terrible. I have the Actiontec, and for me the wireless signal is great, much better than the signal from the router I replaced. But your mileage may vary.....