dead computer data access ?

I woke up last night & saw the clock-radio in VCR mode, blinking 12:00. Must’ve had a surge before the power went out because tonight I can’t get my computer to turn on. I keep an external backup on-site & another off-site (which I recently brought back to update), but of course both of them are out of date. It’s a Dell XP box with mirrored RAID drives.
I have a Win7 machine sitting in the box still, mainly due to software issues. I have some old games that won’t run on Win7 & I have some software on the XP box that is only installed, I don’t have it to put on a new machine. Guess my cutover decision was just made for me!

My choices are to get a power supply & backup data like normal to external drives & then move that over to the new machine or pull the drives, open the new machine & plug it in as a secondary HD. Pros/cons of either method?
If I do the latter, I presume I need to change the switch settings on the old drive to make it a secondary drive. Know how to set them?

Was the computer on or off when it happened? Does the power supply have a red 120-240V slider switch? If so, unplug the power and slide it to 240V and back again and try that.

If it was a surge it may have taken out more than just the supply, especially if it was on. If you only want to recover data your best bet is to go straight to the drive(s).

If the old drive has a wide ribbon cable it’s IDE and probably won’t work in the new computer. You can get a USB adapter like this or enclosure like this.

If the drive is SATA you can go with external or try and mount it internally. That will depend on your case specifics.