Consult information about your motherboard, and ideally:
Track down a support DVD for it, that contains drivers and software.
Follow it's installation process for Audio Drivers.
It looks like Windows XP doesn't have drivers to support your particular playback devices.
I have had this issue on older laptops moving them to Vista and Windows 7.
The 5 audio jacks
you quote is the important thing, not the number of speakers.
It refers to the audio jacks on your motherboard or sound card, not the plugs from your speakers.
If you have multiple audio output jacks on your motherboard/sound card then you have support for surround sound (providing the correct drivers are installed)
The standard jacks are as follows:
Green - Front L/R
Black - Rear L/R
Grey - Side L/R
Orange/Yellow - Sub & Centre
Blue - stereo line in
Pink - mono mic in
2.0 will have 3 jacks - Green, Blue, Pink
5.1 will have 5 jacks - Green, Black, Orange/Yellow, Blue, Pink
7.1 will have 6 jacks - Green, Black, Grey, Orange/Yellow, Blue, Pink
In the pic below, clockwise from top left: 7.1, 7.1, 5.1, 2.0, 2.0
If you want to see in your system properties you need to open up the RealTek HD Audio Manager
(from Control Panel or System Tray icon) and this should show an image on the right that will show you which are available on your system (jacks which are plugged in will be highlighted):
(Error here is because I am accessing this PC via RDP with audio disabled)
Best Answer
It seems like you're missing the driver for the actual sound card in there. My XP device manager lists everything you have, plus one additional one for my on-board sound.
Have you checked the BIOS to verify that it's enabled? Other than that, under the device manager "Action" menu there should be an option for "Scan For Hardware Changes".
Another option is to simply delete everything under the Sound, Video and game controllers and reboot to see if it gets found & drivers reinstalled.