Hi Louise and welcome to Extreme Tech Support - Free PC Help :)
You really don't want to go back to XP.
Not sure if you are asking if you can have XP on the machine at the same time as Win8 ?
This is called "Dual Booting" but again - you should be advised that this is not a good idea as Microsoft are withdrawing support for XP early in 2014 and your machine would then be vulnerable.
Regarding Office 2003
According to the MS Compatibility Center - ( click here ) it is compatible ..... but only the Standard version.
You would need the installation CD.
( not sure if you can only install this on one machine - I assume that this is the case )
There is, however, a totally free option.
Open Office - click here
This is totally compatible with MS Office.
With Open Office Word you need to be aware that this saves in a format that MS Word will not open.
You can, however, select a MS Word compatible format to save in. Not really a disadvantage ......especially for free :)
If you need more information .....just ask :)