BTX to ATX

Hey Guys,

I have a Dell XPS410 that I purchased back in 07. I've changed the graphics card to a GTX470 completed 4GB of Nvidia RAM and added a new PSU plus 3 fans. I still have the same Q6600 Processor overclocked to 3.0 I once wanted to put a thermaltek tower but any cooling tower would not fit properly in the BTX design it appears.

Recently I wanted to overclock my CPU past 3.0 and since I can't figure out a way to change the voltage on an intel motherboard (P965 express chipset) I have grown interested about changing my motherboard for a newer ATX type motherboard. (I would have to switch the Case of Course)

I can run every game (Metro/BC2 lol) perfectly with avg 45FPS but I want to upgrade for the future and remove those walls preventing me from better such as RAM, and a better CPU some day.

I want this so that I can not only continue with my current DDR2 Dual Channel Ram, CPU and GPU, but add another 4GB of RAM plus a Thermaltek tower for better cooling as well as being able to control the voltage in the Bios.

I would like to know if all of my current hardware would be able to do this transition without a problem from a BTX type case to a ATX type. Also I would like to ask for suggestions on mid size tower or full size. Motherboards with a range of $50 to $99USD (Cheap because any board will kick my current's behind easily) with a good versatile Bios for all the kinds of tweaking.

If you require any info, let me know!

Here's a Link to my main computer's specs: http://support.dell.com/support/edocs/systems/xps410/en...

This is also the first time I perform a major change on my PC (It's always been GPU,RAM,PSU,Fans...Easy Stuff)

Thank you so much for your help!  
------------------------------------
Q6600 2.4 @ 3.0 (G0)
GTX470 OC Edition w/ High Flow Plate
Windows Vista 64 Home Prem OEM
Nvidia Dual DDR2 RAM x4 1GB
PSU 650W