That is rather strange. Is the CPU dual core? Also, are you on the same power profile the entire time? Did you reconfig vista to boot on dual core CPUs?
The CPU chip is an Intel Core(2) duo T7500. I have configured the MBR using a third-party tool(Easy BCD) to read the individual partitions at boot-time.
I am not sure about the Power Profile aspect as the options available on XP are rather limited in terms of component based performance configuration. Is there a tool that you could recommend that could be used to standardize the profile across both the operating systems?