Out of curiosity is this your primary system and what do you plan on doing with it? In your system specs it says Linux & Win98 under OS, if that's the case you're going to have maybe 100mb of HD space left for programs & files.

mmmmmm............Power Supply Unit's fan wires were cut and you taped them together with scotch tape, bad idea!!!! this could catch on fire not good!!! remove the tape and use electrical tape or electrical shrink wrap.

15 watts is not enough. like zachary said, take the figure they gave you, and add a hundred. remember, 15 watts is 2 night light bulbs. thats not alot of electricity. It wont be enough to power your computer for more than a couple seconds, and last. As power supplies get older, there is something called Capacitor Aging. The older the capacitors are, the more power they themselves draw. This can result in severe increases in power draw. Trust me, spend the money and get a new power supply. its not worth it to try to use that dell one.

Is this good?:
Diablo PSDA250 250-Watt ATX 80mm Fan Aluminum Power Supply at TigerDirect.com
It has good reputation.

ehh.... Im trying to be helpful, lol, so dont take offense. Always get a good, brand name power supply (I like Enermax, OCZ, Corsair, Thermaltake, Antec, and if cheapness is needed, HiPro. Here, take a look at this one. Newegg.com - HIPRO HP-D3057F3R ATX12V 300W Power Supply 100 - 127V/ 200 - 240V UL, CSA C22.2. IEC, EN - OEM

Hmm im pretty handy at building pcs, a few tips.

-Make sure that when you have 2 hard drives, make the largest the slave, and leave the smaller one to the operating system and general running of the computer. If need be leave no less than 20gb free on your primary drive.

-Make sure you screw the motherboard to the case AND DOUBLE CHECK each silver/gold ringed hole has been screwed through to the case, This is super important and can mean the difference between a working pc, and a non working pc.

-Also, when instaling any graphics card, or any slot inputted divice for that matter, if it dosnt go in with a firm push, it ain't right. So take it out and try get it in, especially with graphics cards. Too hard can damage your device, or motherboard.