Hi, I am building a gaming PC. In the house that I live in (with my parents) there are two routers, one in the attic and one downstairs. I could either put my comp in a spare room which has an ethernet cable or put it in my room with a wireless adapter. The router is 802.11n and it's at most only 20ft away from my rig. Will it effect gaming, and will there be lag?
I'm fairly against wireless use with desktops but if it's convenient, wireless is what most people will choose. However, if you can, always use wired. It will make latency that much better especially when gaming.
I use both depending on where I am and this is my experience.
Similar to what mxsix said, if you can, use a wired connection. As a rule, wired is better.
Wireless can be just as good for gaming, and I've done countless hours of it over wireless, as there are no ethernet jacks in my room. The only problem is interference which sometimes can occur out of nowhere and random lag spikes. Both of which are unpredictable and both of which and really slow down your internet and lag things up.
I guess the bottom line is that both can work perfectly for your needs; wireless can be interfered with from time to time, but wired is consistently reliable.