Just some ideas in no particular order. Why can't you use the DVD like most people do?
"i know i have to modify some files...! which ones....?
also do i need to make bootable HDD first, after formating...? can any body explain steps".
Can you explain what you are trying to do, are you talking about creating some type of hidden recovery partition?
Running Vista Setup from hard drive?
I:\sources\Setup.exe, where I: is the DVD Drive, seems to start the Setup, when you click on Setup.exe. If you do copy to your hard drive, watch out not to format the setup files by mistake.
If you copy the DVD with DOS, you will need to create a temporary FAT32 partition to store them. It might pay you to check to see if a 9x Startup Floppy with CD Support can read the DVD files. Otherwise something like BartPE would be very handy.
BartPE (a mini XP self contained on a bootable CD and run from CD). Needs two CD/DVD drives to avoid swapping disks in and out (which is not too successful).
307848 - HOW TO: Start Setup from MS-DOS in Windows XP
See - "You Receive a File Copy Error During Setup"
"copy the i386 folder from the CD-ROM drive to your local hard disk, and then try to run Setup from your hard disk."
310064 - HOW TO: Troubleshoot Windows XP Problems During Installation When You Upgrade from Windows 98 or Windows Me
How to Install Windows XP on a Laptop with No CD Drive
It has been a Microsoft Policy that when Dual Booting, the oldest gets installed first, a sort of age before beauty policy if you like. Not that every one thinks Vista is a beauty.
I have SATA drives but they are set in the Bios as compatible IDE drives, I am happy with that and never have any problems with drivers and F6 etc.
This thread covers some of the Dual Booting help and Virtual PC alternatives.
XP Pro and Vista dual boot?
thread779-1376301