Do yourself a favor. Get one of these: Ubiquiti AirRouter HP for about $55.

The reason I like these so much is that it's an easily configurable router with 4 LAN ports that is a snap to put in bridge mode and provides great wireless coverage.
You can use the same SSID (wireless network name) and security key as your main router without an issue.
The AirRouter should even auto-adjust it's wireless channel to avoid interference from other broadcasts.

This router uses a Power Over Ethernet (POE) injector to send power over a pair over wires in the same ethernet cable that is used to provide network connection.

You'll just unplug the existing ethernet cable from your PC, plug it into the "LAN" port of the POE injector and then plug the included grey ethernet cable into the injector's "POE" port and the other end into the AirRouter's WAN port.
You will need an ethernet cable to go from the AirRouter to your PC, but those are cheap on Amazon if you don't have a spare one.

One more thing I just remembered: Ubiquiti gear has a software feature called Ping Watchdog.
Basically it allows you to specify "wait x seconds after boot, then ping this IP: (insert your main router/modem)" then you can tell it how often to ping and how many failures to respond it should allow before the AirRouter reboots itself automagically. This is a nice feature that can in the right cases restore service without you ever having to touch the router.

Whatever you do, don't even think about getting a "wireless repeater" or any other form of wireless bridge that isn't getting it's own network connection from an ethernet cable. You will regret it if you do - they are finicky and generally very unreliable.