That's part number XM091 (you knock off the first two letters, the dash and the zero to get from the bar code to the part number), revision A00.
I am not aware of Dell producing one socket motherboards for a two socket machine - though maybe someone will correct me on this. Amongst older machines some boards need an extra VRM plugged in to use the second socket, and some boards need a terminator in the second processor socket when used with a single processor.
Googling for "Dell XM091" (without the quotes) suggests that this is a PowerEdge 840 motherboard.
The PowerEdge 1800 system support for up two generation Intel Xeon processors (code name Nocona and Irwindale)
604-pin PGA package in a ZIF socket
Google says this is a PE840 MB, not a PE1800.
As I said above.
Really, I don't see the point in trying to build up a machine if you've just got a motherboard - especially as there's no guarantee that that motherboard is any good. Low-ish end server motherboards aren't that expensive - but buying a processor, memory (remembering that server memory tends to be different to consumer motherboard memory), power supply and a case could add up, especially when you remember that the power supply and case needed by a Dell server board might well be Dell proprietary.
Without checking, I'm assuming that the 840 isn't one of the higher end servers. If, for example, you found a 2950 motherboard, you'd need a whole bunch of proprietary bits - chassis and backplane, control panel, storage controller card, sideplane, cooling shroud, 4 x system fans, at least one power supply, one heatsink per processor, you should have a pair of expansion card risers and, to make it a usable system, you'll need a a rack rail kit, drive caddies and screws. If you want an optical drive, you'll need the optical drive interposer board, power and data cables. If you want the DRAC 5, you'll need the DRAC card and cables. The only bits that are off the shelf are the processor and memory.
If all you've got is an untested motherboard, I'd say that it's only fit for eBay.