RAM

I currently have 2GB of PC6400 RAM in my new PC, am I going to see any gain if i put a further 2GB in....is it worth the money?

It depends purely on what you're doing, if you do plenty of gaming 4GB helps with modern games, if you do video editing, that helps too, if you just do Windows/office/browsing/listening to music/watching movies/etc for example, it's a complete waste of time and money.

I'm still undecided if 4x1GiB is worth it.

For Vista x64, I cant see any differences for day to day stuff, browsing, email, music and vids - it is all much slower than XP with 2GiB.

I installed Bioshock and it runs exactly the same with 2 or 4GiB, which was surprising, as I was expecting all kinds of problems with it, but didnt have any at all.

I think that DDR2 will only get more expensive, so if you intend keeping your system for a while, it might be an idea to get any extra RAM now while its still fairly cheap.

dropping prices of RAM is like a yearly trend, there is always part of year when they are cheaper.

Adding another 2GB to make it 4GB in my eyes have not really the point, first of all only Vista 64 will see it, even in BIOS most motherboards will report only 3GB. And as Clink said there is no much improvement. All the games now running more than OK on 2GB. Knowing IT market and how fast it progress it might be a change to DDR3 as a standard, maybe than apps will need more memory and Vista will have SP1.

I havent seen any games that show a performance difference between 2 and 4GiB, unless a great deal of multitasking was taking place.

I think at the moment no. The memory market is in a little bit of free fall at the moment so yo have the choice of getting some to try yourself for not that much money before it goes back up again.

They are all valid points, i just want to make my pc as good as i can with out spending loads of money, because i don't intend to upgrade for some time, except maybe a 45NM processor lol looks like it will just have to be a decission i make by myself!

Vista I believe has an upper memory limit of 3Gb out of the box.
However if you wish to run more memory you will need to tell windows it is there by adding switches to your boot.ini files and I think another file with Vista
check MS web sight for more info

32 bit operating systems are limited to 4Gb of addressable memory space by default, which is reduced down to around 3Gb due to needing to allocate addresses for other parts of hardware. It is not just Vista that has this issue, and it is only Vista 32 bit that is effected by it.

You can under a 32 bit operating system enable extensions to use an extra few bits for increasing the memory space, but it requires that your motherboard be compatible. Most importantly, however, drivers have to be written to be happy with this change, and this is often not the case.

As for the boot.ini file changes, many of them, including the fabled "4gb" switch, are a lot of hookum. The old new thing has some good information on these which you can search for in future.

If you're running a 64 bit OS it can have its slight advantages.
Just like others have said I've yet to see any differences from 2x1 to 4x1 and I've never seen Vista use any more than 50% of my 4gb even under intense load.
I even ran 6gb a month ago and not really much difference over 2x1.
IMO get a nice fast, low latency set of 2x1gb and by the time you'll ever need 4gb it'll be time to get a whole new computer. (3-4 years)

::Nevermind:: I guess I just dont pay attention too much..
http://i50.photobucket.com/albums/f3...apiece/nvm.jpg