Vostro 220 motherboard and processors questions

I'm in the process of looking for a Dell Vostro 220 mini tower. From looking this tower up, I've noticed that almost everything about the 220 slim and 220 mini tower have identical motherboards aside the fact both aren't similar in design and chassis. I just want to know what the motherboard model is. I keep running across "Dell part P301D" or "G45 Express" which isn't helpful at all. It doesn't seem as if Intel makes the motherboard. I need to know about this motherboard. It can't just be P301D. That's Dell's part number.

The thing is that I found a Vostro 220 with an Intel Core 2 Duo 2.26gh which makes NO sense whatsoever because I can't find this processor at all, anywhere. It's not a Celeron or Pentium model either. Only processor that showed up was for a notebook. The seller said that the processor is E4500 but that's 2.2ghz. He stated, "Sometimes Windows shows different speeds of the cpu," which is true but it doesn't make the cpu go up in speed unless it's overclocked. It's a new pc, can't be overlocked. This doesn't make sense. Who makes this motherboard????

Next thing is that I found a list of processors compatible with this tower on here. Thanks for that, it's helpful. I also found another list but I can't confim all of them since I don't own the pc. Maybe someone can confim these?:

Intel®Core™2 Quad Q9400,Yorkfield,45nm,4c,2.66GHz,6MB L2,1333MHz FSB,95W
Intel®Core™2 Quad Q8300,Yorkfield,45nm,4c,2.50GHz,4MB L2,1333MHz FSB,95W
Intel®Core™2 Duo E8600,Wolfdale,45nm,2c,3.33GHz,6MB L2,1333MHz FSB,65W
Intel®Core™2 Duo E8500,Wolfdale,45nm,2c,3.16GHz,6MB L2,1333MHz FSB,65W
Intel®Core™2 Duo E8400,Wolfdale,45nm,2c,3.00GHz,6MB L2,1333MHz FSB,65W
Intel®Core™2 Duo E7500,Wolfdale,45nm,2c,2.93GHz,3MB L2,1066MHz FSB,65W
Intel®Core™2 Duo E7400,Wolfdale,45nm,2c,2.80GHz,3MB L2,1066MHz FSB,65W
Intel®Core™2 Duo E7300,Wolfdale,45nm,2c,2.66GHz,3MB L2,1066MHz FSB,65W
Intel®Core™2 Duo E7200,Wolfdale,45nm,2c,2.53GHz,3MB L2,1066MHz FSB,65W
Intel®Pentium®Dual-Core E5300,Wolfdale,45nm,2c,2.60GHz,2MB L2,800MHz FSB,65W 
Intel®Pentium®Dual-Core E5200,Wolfdale,45nm,2c,2.50GHz,2MB L2,800MHz FSB,65W
Intel®Pentium®Dual-Core E2220,Allendale,65nm,2c,2.40GHz,1MB L2,800MHz FSB,65W
Intel®Pentium®Dual-Core E2200,Allendale,65nm,2c,2.20GHz,1MB L2,800MHz FSB,65W
Intel®Pentium®Dual-Core E2180,Allendale,65nm,2c,2.00GHz,1MB L2,800MHz FSB,65W
Intel®Celeron®Dual-Core E1400,Allendale,65nm,2c,2.00GHz,512KB L2,800MHz FSB,65W
Intel®Celeron®Dual-Core E1200,Allendale,65nm,2c,1.60GHz,512KB L2,800MHz FSB,65W
Intel®Celeron®450,Conroe-L,65nm,1c,2.20GHz,512KB L2,800MHz FSB,35W
Intel®Celeron®440,Conroe-L,65nm,1c,2.00GHz,512KB L2,800MHz FSB,35W
Intel®Celeron®430,Conroe-L,65nm,1c,1.80GHz,512KB L2,800MHz FSB,35W

I don't think the quad cores work in this system but I can't say that for a fact. I'm more concerned about the issue I'm having with the motherboard so someone please reply.