First of all, Linux is not made to be a gaming platform, don't be surprised if you have lags. maybe they will work perfectly, maybe not.
I have an hp myself, very similar to you, more powerful 8gb ddr3. I hope Linux works on your machine, I'll talk about what I know. On my PC:
- I had problems with Wifi drivers.
- On ubuntu 12.04 LTS, I had to set nomodeset to make unity work. Newer versions never worked no matter what I do.
- Suspend and Log out mode did not work because of a graphic card issue,
the screen goes black forever, I had to force shut down using the
I had these problems, or at least one of them with every Linux distro I used: Archbang, Manjaro, Crunchbang, Linux Mint (Mate and Cinnamon), Linux Mint debian, Fuduntu, Ubuntu. I hope I didn't forget a distro :)
However, now I'm on Xubuntu 13.10 (The latest version) and it works like a charm out of the box on my PC. Xfce is working perfectly, and for some reason I am not experiencing any errors whatsoever. Besides Xfce is lighter than unity, giving you more recourses to play. And in my personal opinion Xfce is much more beautiful that unity.