Evo laptop

Well I guess this is a mobo problem. Bought a used Compaq Evo Laptop. No hard drive or power. Bought a HDD and it won't go. Tried a boot disk and it says I've got bad drivers or program, but if the HDD dosn't run where's the prob? Tried to flash the Bios but have the same prob. Tried to load XP and when it tries to run windows the first time it starts all over again like theres no HDD. But when I go into setup it will test the HDD and says it's ok. All I get is A disk read error occured, restart.
Ok hears a good one. I've got an AC adapter for it comeing but right now I'm using a 12v off a LCD and the Evo would like 15 to 19v think I might be barking up the wrong tree?