This topic involves mother boards and CPUs so I wasn't quite sure where to place it but here goes:
I have come across an AsRock 939Dual-VSTA mobo that has a slot labelled "Future CPU". The idea is that you can buy a daughterboard (AM2CPU) and upgrade the mobo to a AM2 Socket. I was wondering if anyone has tried this or gotten it working?
The daughter board only supports the cpu as far as I am aware so there is no option for ddr2 800 memory. You will still be limited on the am2 cpu based on the boards bios support for such processors so check how high a processor it can utilize. Then there's the question if the daughter board is still availble and how much it costs.
Don't know what the $100 figure you provide is for as you haven't specified what you get for that.
For less than $200 though you can get a new AM3 board, processor and ram which will outperform anything you can do with that 939dual and move you into the 21st Century.
The only way I'd consider it is if you can get the daughter board and say a Kuma level am2 cpu for around $50.