Nice computer. HP are very reliable. Higher price.
6Gigs of ram is comfortable (But you can never have too much of that)
There are simple softwares available to clean out HP's advertising/junk, and generally tweak it up (try - windows club, or black viper)
PC World is really good reading. But remember, like all magazines, their software/hardware advice is somewhat commercially biased.
Check here -
2) HP ?
4) bleeping computer
A few others, I suppose. Like you could Google 'which graphics card is best'
Another way is to go into the computer shop and ask the pale, geeky looking masturbater who obviously sits up all night playing games!
Nvidea make an excellent graphics card for gaming. Some dedicated gamers will argue over the finer points. (And no matter what you buy, somebody is going to tell you tomorrow that there is a better one - right?)
But I might say - GTX is better choice than GT - 2 Gigs is better than 1 - 560 is a little and 650 is LOTS better than 610 (may be a bit more expensive, sorry)
One thing you better be aware of -
The latest graphics cards are very power hungry. So you better be sure the PSU (Power Supply Unit) is up to the task. 300watts (yours) is surely not. (You got to be careful buying a PSU, too - some manufacturers make claims unrelated to reality). The graphics card will suck up all 300watts power, leaving none for the rest of the computer. Plus they get less efficient when they get hot. Double it is safe (600 - 800 watts)
The screen is good. But if you want 3D - you will need a 3D compatible screen (hey, you don't really need it, but it's also good for watching the latest movies - my own particular vice)
I have various young/not so young people wanting to play huge games on my computer. So I got an external hard drive and stuck all the games and crap on that. I set up a limited account with anti porn and strong security too.(just saying).