Will there much online gaming done on this router, and if so will it be done with both computers or just one? What about video streaming?
It really depends on what you're asking it to do, and how often both computers will be using it will pretty much determine how low you can go. Most routers nowadays are fairly inexpensive that can handle quite a bit of data from more than one machine. However, say someone is playing a game and the other is streaming video, not to mention any other devices that might also be connected all the time (phones and tablets for example) you might want to go up another level.
Personally, I've always found Linksys routers to be of good quality for their price, and they a few different models that can handle different loads.
http://www.amazon.com/Linksys-WRT54GL-Wireless-G-Broadband-Router/dp/B000BTL0OA/ref=sr_1_1?ie=UTF8&qid=1409615048&sr=8-1&keywords=Linksys+-+Wireless-G+WRT54GL+Broadband+Router is $48, and can handle quite a bit for the price.
You can go out and get a fancier brand if you like, but when it comes to routers, imo it doesn't make that great of a difference so long as it can handle multiple devices soundly, which this one can.
If you're doing a lot of high-end gaming though with more than 1 powerful rig, then you want to beef up the transmission rate.