System will not start after installing 2nd HDD, IDE

[ShoobieRat]

What PSU should I have for, a p4 3ghz, 1.5gb ram, 2 ide hdd, 1 dvd rom, 1 floppy, 1 usb zip, geforce 4, sound card and 2 system fans?

Definately anything from 450watts up. Remember the rule of thumb with power-supplies, is that you can never have too much wattage. The computer controls how much it uses and how much comes in, so if yer system is only sucking 400watts, and you have a 600watt PSU, you can't hurt anything.

Its not my windows install, as my PC shuts down 2 seconds after I turn it on, I have sort of solved this problem, by not using my old HDD. AS it always crashes when I use it, even though it never used to a couple of hours ago! i took my old HDD to my mates PC and it was fine.

Don't worry, it's not Windows if that's what's happening. You've got a hardware or BIOS issue going on. Windows only becomes and issue if you actually get to the Windows boot section. Yer 2 seconds is barely into POST at that point.

Finally, how and what is the best way of fitting 2 HDD to a pc, or should i just scrap 2 40gb and get an 80gb?

HDD's are so cheap now, I'd chuck little drives like that and just go with something bigger. See how much you actually need. If yer two 40's were get'n crowded, do a big upgrade to something like a 120 or a 200. They're so cheap. A 120 drive goes for like $70 now.