Are these items compatible with my PC?

[Karlos49]

Hi there! Can someone please help me?
I have an old processor it's a Intel Pentium 4 CPU 3.20 GHz
I am thinking of buying these 3 items,I need help with 2 of them.

The Graphics Card :
http://www.dabs.ie/products/gigabyte-amd-radeon-7850-hd-900mhz-pci-express-3-0-hdmi-oc-8KR3.html

The Power Supply :
http://www.dabs.ie/products/corsair-750w-cx-builder-series-80plus-bronze-psu-8758.html

The Monitor (No Help Required) :
http://www.dabs.ie/products/viewsonic-vx2210mh-led-22--led-full-hd-1080p-dvi-d---hdmi-5ms-speakers-8901.html

So I decided to start playing some modern games like Battlefield 3 and Grand Theft Auto 5,and I need some help.I have been looking for a good Graphics Card for about a day and I came across this.I've been looking at youtube videos and the Card looks very good.I have also noticed that it needs 500W power supply,my PC doesn't have that much, so I decided to get this Power Supply, it offers 750W and I think that will be enough.

So here come my questions :
1) Do I really need that much power or will a 600W Power Supply do the job?
2) Is this card compatible with my motherboard? I don't know if I have a PCI Express 2.0 or a 1.0.
3) One of my friends is telling me that my processor sucks (his isn't any better) it there any truth in his words?
4) And finally,am I making the right choice here,any difficulties or dangers I could encounter?

I don't know the background of this machine or even where it came from.
Thank you!

 

[Augray37]

Unfortunately, your CPU is over 10 years old, and is therefore COMPLETELY inadequate for ANY gaming besides solitaire (for all intents and purposes). Pairing an HD 7850 with it would be a disaster.

I know you may be a bit new to all this, and that's fine, we all have to start somewhere. I really don't mean to offend, I totally understand that you're excited and eager to get building and gaming, but honestly, I would suggest reading up a bit more on PC building before you start shelling out your money. A simple PC building 101 article or video will answer your questions.