I have just talked with absic and he is compiling a list for you at the moment.
Not quite there yet DM
OK Jannie, before we get down to putting together a full shopping list for you, I do have a couple of things that just need to be clarified.
You already have 3 SATA Hard drives but will you be using one of these for your OS or are you thinking of getting a new drive for that?
Your DVD writer & Bluray writer are these both IDE devices?
Do you want to keep your current Graphics card or are you looking for a newer one?
Are you based in the UK? (Just so I can get links for hardware for you if you are)
Do you have any other parts that you are thinking of trying to use in your new PC? (If yes what are they?)
On the subject of OS I too would go for Windows 7 64 bit but, it is worth double checking that any software you have will be able to run OK. If everything is OK then a 64 Bit OS will allow you to have more RAM which will help speed up some of the processes for you.
Sorry that I keep asking questions but I don't want to offer you bad advice.