I did a little digging, here's what I found. Also, if your pc can run Heroes of Newerth on low, you should be able to do the same with Dota2, they are similar as far as requirements, not sure how it compares to LoL but probably about the same.
DotA 2 Minimum System Requirements:
* OS: Windows® 7 / Vista / Vista64 / XP
* Processor: Pentium 4 3.0GHz
* Memory: 1 GB for XP / 2GB for Vista
* Graphics: DirectX 9 compatible video card with 128 MB, Shader model 2.0. ATI X800, NVidia 6600 or better
* Hard Drive: At least 2.5 GB of free space
* Sound: DirectX 9.0c compatible sound card
DotA 2 Recommended System Requirements:
* OS: Windows® 7 / Vista / Vista64 / XP
* Processor: Intel core 2 duo 2.4GHz
* Memory: 1 GB for XP / 2GB for Vista
* Graphics: DirectX 9 compatible video card with Shader model 3.0. NVidia 7600, ATI X1600 or better
* Hard Drive: At least 2.5 GB of free space
* Sound: DirectX 9.0c compatible sound card
Nah I won't quit LoL because all my friends don't have Dota2 invites yet, but once the game goes live I might try to convert you all over to the big leagues.

My cousin just got one, he's bitching about the cost and the data plans, but he really does enjoy it. Expensive though, I need a new phone too but wouldn't use it enough to need an iPhone just yet.
if any one here is familar with computers and won't just slam me for buying a premade one instead of building my own and will help me out I'd appraciate it
I can't build my own because I know nothing about computers but I want to buy the best computer I can for 700 dollars and I have two picks ready if someone will look at them and help me out