A single universal XP image is not likely possible as long as there are
needs for mutilple HAL types. Sysprep images are still limited by HAL's -
so with a Sysprep'd image, you will need one for each HAL in use. Remember
that modern processor architectures such as HyperThreading processors
complicate the landscape to some degree.
RIS in Server 2003 can do HAL "filtering" and unattended installs still
provide correct HAL detection, but both RIS & unattended installs are
significantly slower than typical "image" technologies. There are stated
workarounds available using the major imaging product suites from Symantec,
Acronis, & Altiris, as well as now in SMS 2003 w/OSD Feature Pack. Single
image solutions typically require significant creative scripting using
SMBIOS recognition code as well as "just in time" driver & HAL selection.
List your specific Dell & HP models, the imaging tools that you use, and
people on this forum will probably be able to assist with their own creative
solutions.
Glenn Fincher