The cost of one moment of madness: about Rs 8,000 (one fried motherboard and a side order of a 256 meg memory card).
The hard disk turned out to be salvageable. I have now harvested the Linux machine for parts (except for the above-mentioned items) and have plugged the hard disk into the Windows box. Modern motherboards do not allow you to have multiple hard disks -- assuming that you want to hold on to one of the IDE slots for the CD/DVD drive, so I cannot retain the option of booting Linux or Windows; I will have to manually switch the hard disks for this.
One issue I am currently facing is that I am not able to go beyond a resolution of 640x480. The graphics card is built into the motherboard (Intel 810 chipset). Googling for this shows that this is a pretty common problem, but the suggested solutions (e.g. increasing the video RAM in the XF86Config file) don't seem to work (Update: Tweaking a BIOS setting for video memory did the trick).