XP with Vista

I have a computer with Vista and I want to install Windows XP. When I run the disc from Vista, the Install Windows option is not availible. I also can't seen to boot from the disc. I have already created a 10GB partition for XP. Anyone help???

Basic System Specs:
System: hp Pavilion tx1115nr
CPU: 1.6Ghz AMD Turion X2 TL-52
RAM: 1GB
HDD: 120GB
Graphics: nVidia GeForce Go 6150 Shared Memory
Networking: Dial-Up Modem, T10/100/1000 Ethernet, Wifi 802.11 b/g

Here is a good guide:

http://apcmag.com/5023/dual_booting_xp_with_vista

Note the install order. If Vista was installed first then XP overwrote the Boot Sector meaning that you need to Repair it in order use Vista.

What I meant about being unable to boot was I can't boot from the XP CD-ROM. Basically, I can't get XP installed.

Also, my PC came preinstalled with Vista, so I don't have the Installation DVD and I can't repair the Vista Bootloader after XP is installed.

If Vista was pre-installed and you received no DVD then there must be a Recovery partition from which you can burn a DVD.

You should be able to boot any CD as long as the BIOS is set to boot the DVD/CD drive prior to the hard drive.

Yes, I have a recovery DVD, but I'm nervous about the posiblilty of getting the bootloader repaired. The DVD uses HP's Recovery Manager.

This is the specific guide from that earlier post for when Vista is installed first:

http://apcmag.com/5485/dualbooting_vista_and_xp

I have not done the procedure myself but it appears fairly straightforward albeit a bit time consuming.

Anyway the guide appears pretty detailed. I can offer no more than it does.

I have already read that, but thanks anyway for telling me.

Another approach would be to use a second physical hard drive.

Then it would be just a choice of which drive to boot.

Would it work to install XP on an external drive? The hp tx1115nr is a Notebook PC, as I forgot to state.