A little update - I've now replaced the power supply's circuit board with one from a modern (and working) ATX PSU, the graphics card with a CGA card (which works with the TV with the BIOS timings) and booted into ROM BASIC using a little Windows program to turn keystrokes into scancodes sent over the serial port.
The hard drive doesn't appear to be bootable and I don't have any floppy disks for it yet so I need to write some more code to see if the hard disk is broken or just doesn't have a boot sector, and to determine which RAM chip is faulty (it's only detecting 192Kb of the 256Kb onboard RAM).
Check your inbox ... as far as monitors go, my first one was a NEC Multi-Sync EGA monitor that had the pin-out you need. It was top-of-the-line but cost $650 for a 640x350 16-color display. And it was heavy! I believe I sent it to our local recycler last year, but I wanted to point out that there are VGA-EGA adapters packaged much like RS-232 (serial) gender changers ... if I can find the appropriate one, I'll send it along with your keyboard.
In case you don't know, a 9 pin serial port looks like a CGA port. I distinctly remember learning that the hard way as white smoke poured out of the power supply :)
It doesn't look like a CGA port ... the serial port is male and the CGA port is female (as are early VGA ports as well as the Hercules Monochrome port). Some of the XT's had DB-25 serial ports (the DB-9 serial ports were introducted with the AT) DB-25 parallel ports (so you could drive your Centronics printer).
These machines are so old they don't even have a real time clock, let alone any CMOS RAM on the motherboard. You change the BIOS settings by flipping physical switches, and DOS would prompt you to set the time and date on every boot!
This particular machine does have a clock on a "Tecmar Captain 200044" expansion board - if you have a manual or software for that I'd be very interested. I've found no information about it on the internet (other than people selling them, so it must have been fairly popular at one point).
The hard drive doesn't appear to be bootable and I don't have any floppy disks for it yet so I need to write some more code to see if the hard disk is broken or just doesn't have a boot sector, and to determine which RAM chip is faulty (it's only detecting 192Kb of the 256Kb onboard RAM).