Advice Required On Upgrading My RAM Memory

Hi,

If I'm not in the right place to ask this question, I'd be grateful if someone could redirect me.

I have a Dell Dimension 4500 with Windows XP Home Edition (SP3), fitted with an Intel Pentium 4 2.0GHz (512K Cache) Processor and I've been advised to upgrade the original  256MB RAM Memory, which was already fitted when I bought the PC from Dell UK, a few years back.

The only info I have is that the original part is: 256MB 266 Mhz PCC266 DDR RAM Memory (1*256MB).

I used Dell's (UK) system to search for an upgrade part and it recommended a: Dell 512MB Memory Module For Dell Dimension 4500-400MHz, Manufacturer Part: SNPJ0202C/512 Dell Part: A1461046 at a UK price of £26.48 (GBP), inc VAT & Shipping.

I hope this is enough information for anyone to advise but my questions are:

1) The original RAM is 266Mhz & the upgrade appears to be 400MHz...is this OK?

2) How easy is it to fit the new RAM unit, is it a straight forward part for part swap?

3) Will it require any updating, programming or changes to my system?

4) Will it affect any of the data I have already stored on my computer?

5) Could I go higher with the RAM replacement, i.e. Higher than 512MB.

Sorry if these questions are naive or basic but I'm not that up on computer jargon but I am a competent electronics engineer but not in the computer field.

Thanks,

Tony (Milton Keynes, United Kingdom, Great Britain)