Why are you so intent on turning this into a console/PC war?
.
What the hell are you on about, you were nitpicking about one of the biggest benifits of owning a gaming pc, you were wrong, just let it go.
PC rules for BC, end of, it has nothing to do with consoles.
How much will I have to spend to get a good gaming PC? People keep telling me to use newegg, but I have no idea what to get. I'd like to start with an already built PC because I don't know anything about building a computer.
Look at the 'i need a new gaming pc' thread and ask for advice there, just give them your budget confines (min/max spending) and what you want.
You can get into 1080p 60 fps pc gaming for as little as 450 euros (without OS or monitor), as you spend more you'll get more performance.
I'd say the sweet spot for performance/dollar will be around the 650 dollar mark.
How often do I have to update the guts of it/how hard is it going to be to update the PC
if I'm not particularly knowledgeable about how a PC works?
Depends on what kind of monitor you use (1080p or higher res, 60 hz or 120 hz, or multi monitor set ups) and how high settings you want to play your games on.
Any budget gaming pc built after 2008-2009 will still way outperform the consoles today.
If you build a decent pc now (i5 2500k, 8GB ram, a gtx 660ti or hd 7870) you'll probably be good for years to come.
There is a big bump in minimum requirements coming from the new console gen at the end of the year but again it all depends on what resolution you want to play on (1440p monitors etc) and if you want 120 hz.
At 1080p 60 fps you really don't need much hardware grunt right now and a gtx660ti/hd 7870 seems to be around what'll be in next gen consoles, it should run those ports adequatly, a sandy or ivy bridge cpu shits all over what is rumored to be in next gen consoles.
Can you use the 360 controller on most games? A big reason I never jumped into PC gaming is because I don't really like gaming with a keyboard and mouse.
Yes you can.
And you'll learn to love keyboard and mouse, trust me

everyone does.