PC upgrade time?

[Akka]

Is that a "Intel celeron 2.00GHz"? and if so does that need tweeked to?

Yep, that is the CPU.
"Intel" is the brand (the two main are "Intel" and "AMD", the former being the most famous, but I personnally much prefer the latter, which has on average slightly more powerful processors for a substancially smaller price ; though the battle between the both groups are fierce and common :D).
"Celeron" is the model. It's crap. Pure crap. No wonder you feel it's time to change :D
2.00 GHz is the frequency of your processor. It means how fast it goes (though it does NOT necessarily imply how powerful it is. It's a bit like the RPM on a car : the faster it goes, the faster the car goes, but a different car with a different engine can go much faster with a more powerful engine, even at lower RPM).

As for today, it's quite low frequency, though not completely obsolete.

[red comyn]

See folks explaining things in easy terms works when talking to stupid people

So then what should i be looking for and how much will it cost approx in UKP?

[Crusader4thepeople]

Well the System requirements for RTW is 1.0 GHZ so there should be no problem with rome working, But i wonder what are the requirements for BI?

[Slug For A Butt]

The same requirements I think. I run an Athlon 2000, 1gb ram and an Asus A9600XT. Runs sweetley for me, I noticed most difference when I threw away my old MX440 graphics card, it was a little crappy before that.
I think you will be ok if you throw some more ram and a nicer graphics card at it. You dont need to go the the expense of a new motherboard then. And even if you are technically limited, it is easy enough to swap a graphics card and some ram without knowing about which chipset, bios, FSB speed etc.