Cheers for the reply mate.
Umm for the card I was thinkinh. 60-80 pounds. And what software would I need to run the quad 2.5ghz to its full potential?
I haven't got anything bare the motherboard and processer at the moment, just making some research in what to buy to run cad easily and maybe some call of duty.
I know 4gb tam is plenty, and in relation to a hard drive I will most likely get a 500 gig so does this mean I have to get a more powerful pack due too more fans needed ?
Pretty new to this so sorry if I seem a bit brief
You can't make software utilise all of the cores, it depends entirely on the software. Most games will use 2 or 3 cores, with a few programmed to use 4 cores, but very, very few of these are optimised well, meaning if the code was written properly and made more efficient, even though it can use 4 cores, it would be able to run on full settings on a dual or tri core CPU. It all depends entirely on the software.
But even if a program only uses 1 core, that doesn't mean you won't see an advantage. If you use your CAD program, the internet, be speaking to someone on your instant messaging program of choice and listen to music all at the same time, let's assume each of those use the same amount of processor time and each use 1 core, that would mean (in theory) each would be using 1 core, so each would be getting 100% of the performance of each core, so even though each only uses 1 core, they are getting 4 times the time of if you were using a single core CPU. That is what people mean by "quad cores are better at multi-tasking".
For your graphics card, a couple of £ over budget, but it gives a hell of a lot better performance than the 430 that you posted:
Scan.co.uk: XFX HD 5750 Graphics Card - HD-575X-ZNFC
A 5750 is just about on par with a GTS450, and will be able to handle any game you throw at it.
For your hard drive, if you want 500GB:
Scan.co.uk: Samsung Spinpoint F3 500GB Hard Drive - HDD - HD502HJ
it gives some of the best performance of any 500GB drive, but is a hell of a lot cheaper than those.
And for your question about power supplies, most people always overpower their systems thinking that they will draw more than they actually do. I'm going to assume (just for an example) you are running a Phenom II x4 CPU, and take the parts that I have listed thus far:
CPU - 125W TDP
GPU - 86W TDP
Hard drive - 6W
Memory - ~50-70W
Fans - 2 to 3 W each, let's assume you have 3, that puts you on 9W at most
Mobo - 80 to 90W
Optical drives - 3 to 4 W
All of those are full under load, so the absolute most that your system will be drawing is around just under 400W. You want to be at around 90% load for most efficiency, but you also want some upgrade headroom, so for you the best of both worlds, 450W-500W would be plenty. That would give you enough to have a system with a top end CPU, top end mobo, top end graphics card, several fans, several hard drives, high performance memory, and you wouldn't be pushing the unit at all.
With all of that said though, wattage is a very rough guide. When you actually get into it, features, stability of power and the distribution of amps over the different rails (outputs) are far more important than the wattage.
All of those numbers are assuming that you have a high quality unit too. With power supplies, the phrase "you get what you pay for" applies more than with any other component. You can get a 700W unit that costs half as much as a 400W unit, and the reason for that is the quality of components and features. You lose a lot of over and under volt protection, surge protection, temperature protection, load protection, and you lose a hell of a lot of efficiency too. Also with your lower end units, they are rated at peak power, not their sustainable power. The 700W unit will only be able to put out maybe 450W at the absolute most, any more you are going to blow the unit because it will be under way too much load, and because it lacks the protection, it is highly likely it will clear out other components when it blows, meaning that, because it was damage due to another component failure, warranty won't cover it. You will also
Higher end units are rated at their sustainable output, and they will actually be able to output more than what they say, but only by a few watts before the unit cuts out because it has noticed that load is too high. It doesn't damage the unit and it is quite safe to get it to that point, but it is to stop you from going too far. It has the protection that the other, cheaper units, don't to protect your system. They are also more efficient, meaning more power goes to powering your system, rather than being lost to heat, which is bad for the PSU and for other components, and for your wallet. If you look at the higher quality power supplies, they will be 80% certified, be it 80% certified, brownze, silver, or gold, with 80% being the lowest (but still excellent) and gold being the best. In order to get this, the units must be able to show 80%+ efficiency across the full range of loads from 20% to 100% load.
Brands to buy from are Antec, Corsair, XFX, Sesonic, Enermax, Be Quiet! and Silverstone. There are other manufacturer's that have good units, but across the full range, just about all of those manufacturer's units are very good quality