Adding new hardware for newbie

Hello.

About 6 months ago my computer died. I was installing SP2 from a CD and had a power cut and after that my computer stopped responding. I thought it was my HD and ended up buying a new 250gb for £50 (Western Digital WD2000). Turns out my HD was fine as it worked in a friends computer after I had formatted it!

Anyway to cut a long story short I've been given a new/old computer. Here are the specs...

Pentium 4 1.6Ghz
20gb internal HD (Master, connected through IDEa)
3 X 20gb removable HD (Slave, Connected though IDEa)
128mb RAM (not SD, the other one)
Standard 3.5 floppy
Standard 52X CD ROM (Master, connected through IDEb)
Motherboard? (1 X LPT, 1 X COM, 6 X USB and 1 X Network Card? (Runs at 100Mps)
3 X Fan (1 on Power, 1 on P4 and 1 on computer rear)

I want to put my old bits and pieces in my new/old computer. I have...

1 X DVDRW (4X 8X 40X)
1 X DVDRW LightScribe (8X 12X 52X)
1 FireWire (IEE 1394) card (2 External, 1 Internal)
64Mb Graphics Card?
250gb HD
2 X 512Mb SDRAM (doesn't fit in new computer though!)

In my new computer I have space for 3 major devices at the front (1 Floppy and 2 other). Inside I have space for 1HD. I have 3 of those white things (please excuse my computer literacy) where you plugs stuff like FireWire, USB or Ethernet card, 1 space for a Graphics card and 2 slots for RAM

What I want to know is...
1. What should I put in my new computer for optimum performance? (I like downloading large files and backing up my work)
2. Can I Do-It-Myself (I've previously installed HD, FireWire and Ethernet Card) or should I chop off my arms and get an expert to do it?
3. If so, what should I be looking to pay for it? and
4. If I can Do-It-Myself is there a building guide I can get and that anyone recomends? (or have I just shot myself in the foot?)

Hope this make sense
Thanx for looking,
Sam

You should have at least 512MB of RAM for a pleasant Windows XP experience. 512 megs of RDRAM will cost you a lot of money though.

Putting all the stuff inside the computer is pretty straightforward. You need to know about the master/slave settings of IDE devices.

Everything except the RAM (because its the wrong type) and the Video Card is really straightfoward. Basically you just plug it in where it will fit.

Those white things are PCI slots, your firewire card fits into one of them. It doesn't really matter which.

Your HD will fit in just fine, I would connect it on the same IDE ribbon (the wide thing comming out of the back) as the existing HD. Make sure to put the jumper on the existing one to MA (master), and the new one to SL (slave). By 3x20 did you mean 1 hard drive with 3 20 gig partitions? If so I have a recommendation (based on the assumption you only have 2 IDE connections on your motherboard). I recommend you turn your 250 gig hd into master, and throw out the existing master (not literally, save it, just take it out of the system) and keep the 3x20 (the 60 gig I'm assuming) as slave. This will give you the faster HD as your system drive, and only sacrifice you that one 20 gig HD. If you really want 3 physical HDs you can kill off one of the CD/DVD drives and put the HD there, or you can buy and IDE controller card that will fit into one of the PCI slots.

The DVD/CD drives are replaced in the same manner.

As for the video card, do you have onboard video now? Or is it a card? If the cards are made by the same manufacturer (if its not onboard) you can just shut down and directly swap them. If its ATi and NVidia, you will need to uninstall the drivers (add/remove programs likely), and then also remove the card through Device Manager. Then shut down and add the new card.
If its onboard video, you will still need to do the above process, but when you reboot with the new card in, you will likely have to enter the BIOS to change the video to turn onboard video off. Booting up into the BIOS should send video through your new card, but if it doesn't you can connect to the onboard to change things.