i need to install win7 and xp sp3 with out lossing any system after format

To get Win7 back up and running in a dual boot, First mark the D: drive active in Disk Management, or using free Partition Wizard bootable CD.

Now unplug the C: drive. Enter BIOS setup to Set D: drive first HD to boot (after DVD drive), or change C: cable to D:

Boot into the Win7 DVD Repair console, select Recovery Tools and run Startup Repair 3 separate times to recover the MBR to Windows 7 drive. Repeat until Win7 starts.

Do you want to remove the dual boot now? Perhaps you can research the modem drive issues in Win7 before going back to the retro OS.

I would troubleshoot my Win7 modem driver issues in the related forums here, and research it fully via Google.

If you still want to remove Win7 to format it's drive, then use EasyBCD 2.0 in XP to uninstall the Win7 bootloader in Manage Bootloader tab to revert to XP boot only. Attachment 44012

Now unplug your Win7 drive and see if XP is independent.

If not, the next step would be to run a Repair install in XP to recover its boot critical files to exclude Win7 dual boot. It is really like reinstalling XP except keeps programs, files and settings in place. You only need to reactivate.

For an XP repair install, boot from the CD, ignore the first "R" for repair option, proceed to install until it finds the XP installation and then choose "R" for repair.

After XP repair install, see if Win7 can be unplugged and XP restarts. If so, you may need to mark Win7 inactive to delete and format the drive. Boot into the Win 7 DVD Repair console, open a Command Line and type:

DISKPART
LIST DISK (confirm number of Win7 HD)
SELECT DISK 0
INACTIVE
EXIT