First off I have a Win Me/Win Xp Pro duel boot system.
A good start is to get 'partition magic 7' or higher if there is one, this allows you to partition your hard drive 'without' reformatting it first, this enables you to change the size of your drives at any time with no hassle or data loss.
This is useful in the future when you start to use one drive less as you just move the unused space on one drive and increase the size of the other, with no hassle, or reformatting etc.
I used partition magic 7 and found it very easy to use as it shows the drive space graphically and you just follow a wizard to do it. simple.
Once it's on is it running in the back ground or on the D drive?
no, when you first boot up you will be given the choice of which OS you want to use, so you still will only have one OS running like normal.
Does it have any side affects and what is the draw off the cpu.
side effectsare minimal but...
say you have drives:
C:Win 98
D: Win Xp
dont use Application programs across the drives.
ex, you have AH installed on C: drive but you open it while you are useing XP on the D: drive this can result in weird stuff happening/corrupting data ex.
so if you wanted to use AH under XP you would 'ALSO' have to install it on D: drive.
so in effect you have doubled the space it takes up on your computer.
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Ok tech type stuff.
When you format the drive you will choose one of the following formats either NTFS or FAT32 now.
If you make them both the same you will be able to see both drives but for example you make:
C:Fat 32 Win 98
D:NTFS XP Pro
in this example if you boot up in XP you will see that you have two drives C: and D: and you will be able to get data saved on C: and open it/copy it onto D:
If you boot up in Win 98 you will not be able to see the D: drive. It will be as if its not there.
It you make both drives FAT 32 you will be able to see both ways.
I dont think you can make them both NTFS as WIN 98, Win ME can run on it as they are not NT based OS's like NT4,WIN XP,WIN 2000.
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I have both my drives as Fat 32, and my system is very stable and gives me very few probs.