IE7 Changes Boot Sector MBR

Hi, I am using Win XP/SP2 With IE7, AVG 7.5, Spybot, and sometimes Windows Defender. All have latest updates. No Virus/Spyware is found, but AVG reports a "Change" in the MBR Boot Sector after IE7 or Windows updates.

1. Why does Microsoft change the MBR Boot Sector?

2. Is there a program that will back up the MBR and restore it?

3. Should I worry about the change?

Thanks for the help.

Bit of info here knotwurthy

http://forum.grisoft.cz/freeforum/read.php?8,101134,103120