New Graphics Card

what hardware do you have ? what do you want the card for ? if for gaming, what resolution is the monitor ?

Just a standard Quad-Core computer i bought around 2 years ago all standard spec, it's 22" not sure on resolution. I will be playing a few games on it but i'm really just looking for a graphics card with a HMDI port so i can put my computer onto my 42" TV.

What things do i need to look for when looking for one? how do i know if it is compatible with my computer?

you need to say exactly what you wanna use the card for as some games need a better card than others

I only play Age of empires III on PC so that will be the only game i will need it for

We need to know a few things about ur pc. The PSU is a key factor as it will have to power the GPU in the first place, you can find this bt opening the side of the case and tell us the make/number on the large power block.

The CPU and RAM can be a factor too and to find this out you just need to right click my computer and check specifications. Programmes like ccleaner, cpuz and speccy will tell you what u need to know and then just post the results here

You planning on just hooking it up to the tv to watch films and play the odd game then? if so what is your budget too

Yep that's correct and looking at around £100  

We'll need to know the model/make of your PSU.

You can consider a HD 6670.
http://www.amazon.co.uk/Sapphire-11192-12-20G-HD6670-Gr...

That's great. Just for future reference how did you work that out? What will i need to know if i want to look for another graphics card?

So i have

Wattage
PCI-E

is there anything i need to look at?

Actually I didn't work it out..  

But a HD 6670 is ones of the best entry level cards that consumes little power, and it doesn't need an external pcie connector.
It only draws power from the PCI-e slot.

Wattage is important.
You should make sure that your PSU can handle the new GPU you're looking for.
Also, you should make sure that your CPU wouldn't be a bottleneck for it.  

So in the future aslong as my wattage is good enough from my PSU and it fits in the PCI-E it will work?

A Radeon HD 7750 is a good choice, but the OP really doesn't need that much power and it costs more too.

Yes, yes it should.
And if you have a case that is big enough, if you go big.  

Fantastic i thought there was alot more to it so i can just look for them 2 things and all is good a graphics card should work  

Thanks

You're right about that.
But considering the OP only plays AOE III, I don't think there's much use for a 7750. Although, on a long term perspective, it may prove to be useful.  

LOL, you're right about that.
But I wouldn't call the HD 6670 as being a bad card.
It competes closely to a 9800GT and it's really a good card for people who do light gaming and for has got a low budget.  

My mate has a Nvidia GT240 DDR2 lying about which is PCI-E will this work in my comp i have tried having a look at some specs but it doesn't say what wattage it needs also when i was searching i saw DDR2/DDR3/DDR5 what do these mean?

We still haven't gotten much info on your PSU.
What's the make/model of the PSU?

I'll try get that information tonight as i'm at work atm!  

Take your time and then report back after you get the info.  

Trying it won't destroy my computer in anyway will it? ha don't want to risk ruining it!

It will do it no harm whatsoever

Also ignore the DDR on GPU's as it wont affect you

get a amd 7770

That's above the OP's budget, a_tractor.  
And we don't even know of the OP's PSU yet.

I'm Back! my PSU is only 300w could i still use the GT240?

Is it a generic one?
What's the manufacturer?

the graphics card is a nVidia Geforce GT240 but has "palit" on the fan so i think that is the manufacturer

I was asking about the manufacturer of that 300W PSU...

Didn't get the manufacturer   does that matter?

a 300w psu will rut the gpu fine.

the gt 240 that is.

Yes, it does.
Maybe it is a generic one. Did you get it with your case?
But a 300W should be okay to run a GT240.
How much Amps does it deliver on it's +12v rail?

Yep bought the computer as a whole, Not sure what amps it does.

On the side of the PSU there should be a chart like this one.

Check the amps it delivers on the +12v rails and report back.

+12v 19A Max not to exceed 268w i believe hard to work out the writing ha

I guess that should be okay.