Windows 7 and XP on one PC

[Hateshinai]

I want to install Windows 7 as a second operating system on my PC which is already running XP. The plan is to have XP on one hard disk and 7 on another. What is the best way to do it. Should I physically disconnect the HD with XP when I install 7? If I do that will I have to physically disconnect HDs depending on which OS I want to boot or will I be able to choose between them on powering on?
Please keep in mind that I got the IT skills of a one-legged Zambian donkey with advanced senile dementia.

[emwearz]

Just create a partition on your drive, install Windows 7 to it, when your computer starts up it will give you the choice which OS you wish to boot.

(I have done this with 3 OS's in the past

[Hateshinai]

The HD which has XP on it doesn't have enough space for 7 as well. I tried installing on the second HD (I unplugged the XP HD) but it won't install - something about the HD having dynamic volumes (freshly formatted and olumes deleted using disk manager).
It seems I might have to install over XP.

[ZeroAX]

don't disconnect the HD and just try installing it on the second one

[Niode]

All you need to do is install it on the second hard drive. The bootloader will see that you have 2 windows OS on there and give you the option to load either.

There is a caveat to this though. The bootloader will be installed on the other hard drive. So if anything happens to that drive's Master Boot Record you will lose access to both operating systems. If this happens there are recovery options in the Win7 install disc (if it's the same as Vista, anyway) and you can do it, but you need to know what you are doing.

The reason I tell you this is because I had the exact same setup, only that I was using Vista and Win7RC, the drive with my Vista install on it died, I couldn't boot into my system at all because the bootloader was installed on the drive that died. I had to create a new bootloader and write it to the MBR of the new drive, then repaired install and I was back into a bootable OS (this isn't an automated fix and will take some knowledge of DOS and how NTOSLDR works. It took some head scratching I can tell you!

[Hateshinai]

Thanks for all the advice.
This is what I have done up to now:
1. Solved the whole "dynamic volume" problem. Google helped
2. Cloned my whole XP HD to the bigger HD
3. Physically disconnected the original XP HD.
4. Resized the partition on the clone HD to take advantage of the bigger size

Now I am running XP from a cloned HD.
I will try to install 7 now through the update method which should preserve all my programs and file.
If the manure hits the fan I can always boot back to XP from my original XP HD.
See you guys soon.
Hopefully...

[PharmaceuticalCowboy]

I just want to ask why you want to do this? As I understand it Windows 7 has a full fledged XP compatibility mode so you don't run into problems.

[fastbilly1]

I am guessing he doesnt want to reinstall everything.

[Hateshinai]

I just want to ask why you want to do this? As I understand it Windows 7 has a full fledged XP compatibility mode so you don't run into problems.

Actually the XP compatibility mode is meant for business applications and not games etc, so I was expecting problems. Besides, I don't think the Home edition of 7 has that feature.
I am using XP to post this because I still have to get a W7 compatible anti-virus and drivers for my modem.
I didn't manage to do an upgrade (probably since my XP was pirate) but it was a smooth clean install and all my non-application files (photos,etc) were transferred automatically into a folder called "windows.old" so I didn't really have to use my back ups.