Why do you descibe having a problem with Win7 and then list your OS as XP? This is confusing.
Do you have a Dual boot?
Please post back a screenshot of your maximized Disk Mgmt drive map with listings, using SNipping TOol in Start Menu. Attach file using paper clip in reply box. Tell us what is on each partition.
Was there ever a time when the PC started normally? What was different then? What changes were made before the slow boot began?
Read over these Troubleshooting Steps for Windows 7
while we read your Disk Mgmt. screenshot.