Replacing all of those components (after the motherboard) will actually invalidate the original windows licence btw. The OEM (original equipment manufacturer's) licence only allowed for a maximum number of components to be changed before it became a new computer requiring a totally new licence, so your options will be restricted to the free o/s after such a major overhaul. And to be honest at that point you might be better off buying a low end spec desktop machine that is end of production and ex display from one of the major retailers for around £200 and upgrading that as a project....
(Also used to a hardware engineer (laptops, desktops, printers & servers) as well as a software engineer)
Be very careful when removing RAM, Motherboard or CPU.... ALWAYS.... wear an earthing strap that has been tested as static will destroy these components! These wrist straps are not expensive and work by having a capacitor in contact with your skin that takes a few seconds to equalise the charge between you and the machine, so a bit of wire is of no use, as its the gradual discharge that is the key factor. Also ensure that any new components are in their correct metallised packaging and are kept in it until fitting I.e. DON'T take em out for a quick gander/drool before fitting and then handle them by the edges only. This was dinned into us on the "City and Guilds" Computer Technicians course I passed a few years ago,
I only got onto this course by "accident" in that I wanted to learn how to operate a computer but instead learnt how to be a computer mechanic, good fun though.
Holding the bag in one hand whilst removing the component with the other is deemed to be safe/safest providing the capacitor is within toleranceI use ESD straps on a daily basis - and they must be grounded to have any real affect. If you are at the same potential as the chassis, then both of you can still cause electrostatic discharge to a component once it leaves the ESD bag. Note: only the INSIDE of a ESD bag is safe - I see lots of customers place the board on the outside of a bagOH
There is a site that is trustworthy (cannot remember the name but know it when I see it) that sells components and via internet will check your computer and see what can be upgraded.
Pity it does not have a linux scanner , i have an older system ( 2 gig ram, 3800 dual core , 80 gig HDD ) that i would like to add ram too but i am not sure if thats the max the mobo will take but as the scanner does not run even under wine and i cant find anything on the mobo to say what model it is .Curial, we get memory upgrades for macs from them... work well.
http://uk.crucial.com/gbr/en?gclid=..._id=Sw008ENIYWYAAFzyq40AAAOA:20140513161217:s
[Edit: jeffmcg has beaten me to it, but 2 recommendations are better than none!]