Trackpad and Pointing Stick Not Functioning

I replaced the bottom case assembly on my Dell Latitude D630 last night.  After I took 50 screws out and only put 49 back in (no matter how careful I am, this always happens), I fired it up and got an error message saying something about the BIOS.  (I think I unplugged the BIOS battery from the motherboard.  The system date and time were off - it had reset to July 23, 2007)  But after looking around in the BIOS settings, it looked like everything was recognized (memory, hdd,  processor, etc.), so I tried again and XP started up fine.  I think I might have had mouse movement for a fraction of a second after XP loaded, because the pointer was not dead center, but after that there was nothing from the trackpad or the blue pointing stick.  It is possible that I imagined the initial movement though.

I plugged in a USB mouse and looked around in the mouse settings and it looked like XP didn't even recognize that it was a laptop.  There were no trackpad settings to try and adjust.  I searched the internet and found a driver, installed it, and restarted and nothing.  Searched and found a different one, installed and restarted and still nothing.  Everything else is working just fine.  Everything on the keyboard is working fine.  I took the keyboard off again and unplugged the keyboard from the motherboard and tried to find if I missed a connection, but the pointing stick cable is connected to the keyboard cable, right?  I'm not sure about the trackpad though. 

This is not the OEM version of XP I am working with.  I received this laptop secondhand and installed a generic version of XP some time ago.  But it was working just fine until I unplugged everything and plugged it all back in.  So I am wondering if there is some connection that I am missing, or if there is some specific driver I should use, or some way to get XP to recognize that hardware.  Also, wondering if maybe just reinstalling XP all together would get it working.

I was just so proud of myself for taking the darn thing completely apart and rebuilding it (my first such experience with a laptop) and this trackpad thing is just ruining all my good vibes.  Any and all help is greatly appreciated.