Hello & welcome to the DriverPacks forum!
Sadly, many OEM's have all-but given up support of Windows XP.
It may be easier to acquire an external audio solution such as an inexpensive USB-Audio solution; however you may pay a price in audio latency. If such a thing concerns you, check my signature for "D-P-C Latency checker" by the venerable Thesycon.de. In addition, the inexpensive external audio solutions are unlikely to include HD Audio support.
To attempt to find support for your audio chip, if possible, we must find some facts.
From Microsoft Update, we can intuit the type of Audio Chip you may have.
http://catalog.update.microsoft.com/v7/ … 26DEV_506E
From that list, it would appear to be a Conexant chip.
It appears that we may be looking for either a "Conexant 20671 SmartAudio HD" or "Conexant 20672 SmartAudio HD".
Does that align with your system specifications?
Another piece of important information would be included in the driver that dell makes available for your note now.
Note that the likelyhood for a Vista or W7 driver to work properly in XP is fairly low.
However; some XP drivers might be included in driver packages for other Operating Systems.
The size of the download may be one indication.
One possible source could include station-drivers, although their sources are obscured.
From the dell driver, it would appear that you would be looking for "; SmartAudio package [G]", unlikely to be found for XP. It would seem that looking for an XP driver may be akin to a "wild goose chase".
Otherwise, you may be looking at using "XP Mode" or otherwise Virtualizing your system should XP be of absolute necessity. One other possibility could be to use Wine in Linux.