Installing Linux and Windows with new drive
To install any distro of Linux on your computer first buy a second hard drive of about at least 120GB capacity.
Make sure it is the same type as the one you already have.
Hard drives in older computers are usually IDE types. These use a flat ribbon 80 core cable with two connectors for data transmission and a multi-strand cable for their power supply.
On the back of the drive you will see a connector with pins for the ribbon data cable and a connector for the power supply.
Both connectors are shaped to prevent connecting them the wrong way round.
Between these two connectors you will see 8 pins in a 4 x 2 arrangement.
One pair of pins might be connected by a jumper.
These pins are used to set the drive to be either the master (primary) drive or the slave (secondary) drive.
Some hard drives indicate which pin pair select master, slave or Cable Select (CS).
If your drives do not have these indications you might have to Google the drive's manufacturer and the drive model to find out if you can get to view the drive's user manual.
I am not allowed at this stage to post URLs to this site so I will have to suggest that you Google "Cable Select" and see what you find for details of setting your drive's to cable select.
Plugging the end connector of the ribbon cable into a drive makes that drive the master or primary drive whilst plugging the middle connector into a drive makes that drive the slave or secondary drive when both are set to CS.
You may need to put your existing drive lower down in the case to avoid twisting the data cable too much.
Now for the really interesting bit.
Take your existing drive holding Windows 7 and, after setting it to CS, connect it to the centre connector on the data cable.
Install your new drive, also set to CS, into the case and connect the end connector of the data cable to the drive. Plug the power cables into both drives.
Insert your distro CD or DVD into the CD/DVD drive and restart your computer.
When you restart your computer make sure that you set the BIOS to cause the computer to boot from the CD/DVD drive.
After booting from the CD/DVD you can try out the distro in Live mode or install it directly.
This procedure is quite simple and only needs minimal input from you.
The great thing about installing Linux in this way is that your original Windows drive does not get its master boot record (MBR) overwritten and you can restore it to be your master drive by simply plugging the end connector of the data cable into it.
Don't try to install the Windows drive into another computer. Microsoft appear to have written Windows to recognise only the hardware on which it was originally installed and it won't run on other hardware.
You can also enter the BIOS set-up routine on start up to select the Windows drive to boot first if that is what you prefer.
The primary drive with Linux will have GRUB written to its MBR and will present a boot menu for you to select to boot into Linux or Windows on start up.
Later, when you feel confident you can modify file names in /etc/grub.d.
Changing the file name of /etc/grub.d/30_os-prober to /etc/grub.d/04_os-prober changes the order in which the scripts are run and Windows will be first in the boot menu and will start automatically when you start your computer