Need Advice on building my own gaming pc

To start off I'll explain my situation of a 16 year old which works in construction in the summer for my source of income so I'm not exactly swimming in cash but I have found many hours of fun from computer gaming on my laptop but I have several games which are very slow on it and I really want to play ARMA 3 and the Day z stand alone when they come out so I think it is time to get a desk top pc.

I've recently watched over and over a video by " jackfrags - epic gaming " channel on youtube entitled " Steam box how to build your own gaming pc"

I'm not a complete stranger to pcs as I have used them a lot and have done some work on getting old pcs working again so I have a good idea of the components I need.

As the video's pc was to keep cost under 300 British pounds ( $479,17) I descided it was a good starting position but some of the things about the pc I wanted to improve but keeping the cost in check.

these are the components I have picked out for the pc build :
Raidmax tornado tower ATX-328 WU case with coolant fans allready installed

intel i3-1200 3.1ghz dual core LGA115 Processor

MSI H61m-p31 (g3) LGA1155 motherboard

Corsair XM53 8gb (2x4) 240 pin DDR3 RAM

XFX Radion HD7770 1gb GDDR5 video card

Lite On IHAS124 dvd-rw optical drive

Seagate baracuda 1tb ATA-600 Hard drive

Corsair builder series CX500 v2 Power Supply

I have never built a computer before other than taking old ones apart and puting them back together so I came here to make sure these would be compatible as I think they will work but I don't want to order everything and it not work.

If I did use these components , those of you with similar specs would you please tell me how its preformance would fare in gaming.

Also I wondered if there were certian components which would bottle neck the system and hold it back or if you would reccommend different brands due to better reliability or features.

I also wondered if it would be better to get a liquid coolant system for the processor or a heat sink fan which comes with it will do fine?
I honestly am very nervous about building this pc and want to get it right so I came here because there are so many people who know craptons of things about computers.