This is my first build as i'm only 15. I'm very pleased with every component so far. The reason I went with the G3258 is because of its great overclocking potential, already having overclocked to 4.3GHz with 1.343V running through the motherboard with the stock cooler.
G3258: Overall a fantastic CPU that everybody should use for a budget build, also you can easily upgrade the processor later as it is using the LGA1150 socket.
Motherboard: Again great motherboard from Asus. Great build quality, suitable for overclocking, although if you are planning to heavily overclock then you should probably spend more.
RAM: Nothing much to say about RAM apart from the fact that it works, the only problem is that the CPU and motherboard combo only support up to speeds of 1400MHz.
Case: I was skeptical about this case as it was so cheap but i had absolutely no reason to be. Fantastic build quality, great cable management and expansion options. You can't go wrong with it at this price and it looks great too.
PSU: The power supply that i went with may not be the one in the parts list as mine is fully modular but the name is the same. Overall, its really great, really quiet and looks to be really reliable and sturdy.
Storage: The reason this part isn't in the parts list is because i got it from my dad for free which is pretty nice. Its a Crucial MX100 250GB SSD, which is plenty for me, but if you're getting into PCs i'd highly recommend getting a 120GB SSD and a 1TB hard drive.
GPU: As you've probably already noticed that this build doesn't have a graphics card. This is just because both AMD and Nvidia are coming out with new cards and i haven't been able to decide which one i want. Also most of the games that i play are fine on the integrated intel hd graphics. If you want to go budget then i'd highly recommend the R7 360 as i had one in my other PC and it is unbelievable at 1080p. If you want to go a step up, then buy the GTX 950, as it is really great value and kind of replaces the 750Ti as that card is no longer really worth it anymore. But the 2 you should really consider is the GTX 1060 that is coming out very soon or the RX 480, both cards would demolish all games at 1080p and 1440p so they really are great value.
UPDATE: I managed to get myself and Asus Strix R7 370, having owned an R7 360, i didn't think it was going to be that much better but i was wrong, it really is on another level and gaming at 1080p should be no biggie for this card. I also got the 2gb version not the 4gb is because this card can't really handle new games at 1440p or 4k at high settings which are situations where you'd need more VRAM, and at 1080p 2gb VRAM is more than plenty.
UPDATE 2: I have now returned the R7 370 as i found a great deal on ebay for a GTX 780 for £110 and its doing fantastically well. I am aware of the bottleneck but its still performing a lot better than the AMD card for £16 cheaper. It is actually the reference design as you can see but i couldn't find that on pcpartpicker. Because of the bottleneck, in a couple of months time i'll be upgrading to either an i5 4690k or an i7 4790k and of course therefore the motherboard as well. In case you're wondering the PSU is supplying power perfectly to every single component and has allowed me still to overclock the card by +225mhz on the core clock and +300mhz for the memory. As you saw from the picture i've also added 2tb WD green hard drive for mass storage.