Hi,
I have recently built my own system and so i can relate to what you are asking.
First, looking at what you are planning on using the PC for, the specs that you have chosen seem reasonable, although if I were you I would get the CPU that I have, which is the AMD FX-8120 8 core, which is about the same amount of money, and I have mine easily over-clocked to 4.5Ghz due to the unlocked multiplier. I would strongly reccomend this as the faster the clock speed of your CPU, the better you can do things such as gaming and movie/picture editing. REMEMBER TO CHANGE YOUR MOTHERBOARD IF YOU GO FOR AN AMD CPU, DIFFERENT SOCKET ON THE ONE YOU HAVE CHOSEN! =)
Next, are you planning on using WIFI? If you are, have you included a wireless card in your specs? I cant see one in your post. just a thought.
Your HDD could do with upgrading if you ask me, 5200RPM spindle speed? Your PC Read/Write speeds and boot up times wont be very good. Perhaps upgrade for a 7200RPM? Also, are you sure you are going to need 1.5Tb? If you are planning on hoarding loads of movies and songs etc. then fair enough, but a 1Tb or even a 750Gb would be adequate. Also, have you considered buying an SSD? If you bought one and installed your OS onto it you defiantly wouldn't regret it, I assure you. its what I have done with an OCZ 60Gb SSD , and my boot up times have been halved to 20 secs. =) But if you did this, then still get an HDD
As far as your GPU is concerned, it entirely depends on how much money you are willing to spend? I have an EVGA Nvidia GeForce GTX 550Ti 2Gb, which i have overclocked slightly using the EVGA utility that comes on the drivers disk, and I can play graphics intensive games like Skyrim on high Graphics settings. I purchased this from Amazon for £120, and a 1Gb version was available for £90. However if you're looking to spend a little less on your GPU, then i can recommend that you check out a few benchmarking websites, such as CPU Benchmark for the GPU for you. Just bear in mind that if you buy a graphics card that is 2 expansion slots high, you will cover up one of your PCI ports.
If you go for some of the changes i have suggested, like the CPU and SSD, and if you buy a graphics card like the ones I have suggested, you might want to upgrade your PSU, as 450Watts may not be enough. Plus the 12+volt rail may not be strong enough. I would go for the Corsair CX600 600Watt personally. same price and better.
I know that this is alot of changes, but the price wont be effected none, and it will mean that your PC will easily do what you want and more.
I hope that this has helped.
If you have any more questions, please do not hesitate to send me a message.