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#11
You need the Windows Firewall which is fortified by all of the MS Security Updates, along with a lightweight uninstrusive free AV like MS Security Essentials.
Type Disk Management in Start Search box, open it and make full screen. Then use Snipping Tool in Start Menu to create a Rectangular Snip of the drive map and listings. Post back using paper clip in reply box.
It is likely you'll need to clean reinstall. If you want to keep XP, use DVD to delete and format the Win7 partition and it should configure the Dual Boot with XP again if XP is not corrupted.