Hello! Welcome to TPU!
It is worth it if you're willing to put some time and effort into it. You'll need a few parts. Depending on where in the world you live, those part may or may not be easy to come by. So let get started.
As you already have the PSU, you will need at least 1 stick of ddr3 ram, a cpu/heatsink, a keyboard & mouse and a GPU for it. You'll also need to be able to jump the power pins on the board to turn it on and off.
As shown in the picture below, you'll need to short the two pins taken up by the switch header shown;
(Image courtesy of the Dell forums)
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If you do a post test and you can get into the BIOS, you likely have a working board. Just an FYI, the T5500 motherboard is, as you can see, a big boy. You'll need to buy a case that will fit EATX motherboards. If you can get this far, come back and we'll help you get the rest of the way!