Dell XPS 400/ Dimension 9100 case mod to ATX or upgrade processor?

[Kajigger]

I've recently acquired a Dell Dimension 9100 . It's completely operational, but whether I should keep it or not has come to mind. According to Google, the best processor I can put on it is a C2D. On my current build, I have an i3 2100. The case is a full ATX case and it's huge. I have two options

1. Keep it as-is and upgrade to a C2D Edit: And keep it as a secondary
2. Attempt to mod it and replace the internals with my current PC (ATX board)
3. Trash it.

Does anyone know of a tutorial or something on how to mod it? It's a BTX style case. I've also found this on eBay: http://
That is an HP 6200 BTX motherboard that has an LGA 1155 socket, so I would just have to cut out the I/O panel.

I'm looking for opinions, so what do you guys think? I'm not buying a new case though (Reasons).

 

[Quixit]

1. -> That's 2 generations behind your 2100 which doesn't make sense.
2. -> You could try that but it would require some work, probably including cutting and replacing the power supply because BTX is not compatible with ATX boards. If you do this make sure to measure and mark all your cuts properly and to plan ahead.
3. -> This is the easy route.