installing windows 7 ultimate

OK, hope things go well for you.

It depends on whether you want Win7 to configure a Dual Boot menu as it will when installed while another Win7 is on the same or another HD. This interlocks the HD's by placing the boot files on the original OS partition and requires surgery to remove it later to write the System boot files to the newer OS. Startup Repair - Run 3 Separate Times

If you unplug the old Win7 during install of the new one, after install you would set the preferred to boot first in BIOS setup, then use the one-time BIOS Boot Menu key to trigger the other OS HD to boot when needed. This keeps the HD's independent so either can come and go as you please.

Adapt these steps to get a perfect install: Reinstalling Windows 7

Check now to see that you have the one-time BIOS Boot Menu (BBS) key by looking on first boot screen - I'm not sure Packard Bell's all have one.

If not leave both HD's plugged and let Windows config the Dual Boot.

If so, when you unplug old Win7 to install new one, set the target HD as first HD to boot in BIOS setup (after DVD Drive).

After install when you plug back in the original OS HD, leave it as it is in BIOS setup but use the one-time BIOS Boot Menu key to boot the old Win7.

If both are left plugged in then Windows installer will configure a Dual Boot menu which will show up right after BIOS POST for you to choose which OS to boot into.

The default OS and timeout on this menu can be adjusted at Computer>Properties>Advanced>Startup tab, or one or the other OS's can also be hidden.

To get through the Boot Menu menu quickly I set the preferred OS to boot the default OS in 5-10 seconds because if I want to boot the non-default I will usually know it and be ready.

This will place the System Active boot files on the old OS partition, so if you want to remove that HD later you'll need to mark Ultimate Active in Disk Mgmt, then boot the Win7 DVD Repair console or Repair CD to Startup Repair - Run 3 Separate Times until Ultimate boots on its own and shows the System Active flags on its partition.

I may have misunderstood, but what's the reason you'd want to install two copies of the same OS?