Lost Win7 MBR


I have 2 drives. I appear to have lost the Win7 MBR on drive zero as when I boot into drive zero I boot into an existing WinXP system but not the Win 7 one which I want.
(This may have been caused by my having previously installed Winxp on drive 1. The installer seeing an existing XP partition on drive zero linked to it, and set the mbr on drive zero to WinXP. I am surmising.)

I can however boot into the Win 7 on drive zero from my drive 1 (which has a Win7 MBR, bootmanager, BCD, etc). I find that the Win7 system in drive zero runs fine and Easybcd functions as expected. But I can't write the Win7 MBR on drive zero in order to be able to boot into Win7 directly from drive zero.I have tried using Easybcd from the Win7 drive zero and from the Win7 on drive 1.

There doesn't appear to be a way of specifying on which disk the mbr is to be created.
If you don't have a W7 DVD, create a repair disc
Control Panel > Backup/Restore > create repair disc.
Disconnect HDD1
Boot the DVD/repair CD
"repair your computer"
"startup repair"
(3 times)
Boot HDD 0 W7
Run EasyBCD
Add an XP entry (auto-configure)
Reconnect HDD 1
Add entries for the OSs on HDD1 to the new BCD on HDD 0.
Can you give us a more detailed description of exactly what partitions you have and know what hard disks?

Generally the boot process proceeds from the BIOS to the master boot record on the first hard drive or hard drive zero. If you use the Windows recovery CD that Terry60 suggested that should repair the boot into Windows 7.
Thank you all for your replies. I'm afraid I made a pig's ear of it all and ended up having to isolate drive zero and rebuild it. Everything is now fine with 2 drives working independently and with the ability to access applications from either drive.