@Desolator
Don't get depressed! We all have problems with our computers.
I don't know about your previous A1200 experiences so here goes a description of how to fit it together:
To get the keyboard fitted in your A1200 correctly it's got to slide in to the spaceholder at the lower end of the A1200 bottom chassi.
I've mad a small "schematic" here:
http://carls.1av10.nu/a1200.gifThis is actually pretty tricky! I've managed to get it wrong a couple of times...
Also make sure that the HDD cradle is seated correctly on the motherboard and that no cables get in the way when fitting the keyboard.
The top part of the chassi is supposed to snap onto the bottom part.
Right, when (if?) you manage to get your Amiga back together:
Get "Miami32b-020.lha" and "Miami32b2-main.lha" from aminet. These are archives that are already split up and so it fits on two 720kB floppy disks without any extra fuzz. You'll just need lha for Amiga.
This is just a demo version but AFAIK it'll work with your PCMCIA NIC although it has a time-limit of running for 30 minutes at a time. This should be enough to get you started!
Secondly, when you've got the cash, I'd recommend you to get some kind of CPU card or at least a trapdoor memory expansion.
Good luck! I hope you'll get this running and that it won't put you off!
Edit:
Another way to get big files from your PC to your Amiga would be to get a null modem cable (make sure to get one with both 9-pin and 25-pin connectors) from for example Kjell&Co. Then get terminal program for your Amiga (NComm will fit on a 720kB disk) and fire up hyperterm on your PC. The A1200 should operate safely at 28k8 while higher speeds MIGHT trash the transfer.