XP does in fact come with an implementation of ASPI however it is only a partial implementation (it only has what the cut down version of Roxio that is integrated into XP needs to get by) and is not sufficient for the needs of most rippers.
Ahead's Nero also comes with a version ASPI, but this version is also incomplete and not sufficient for the needs of most rippers. If you have installed Nero then it probably means that you have two versions of ASPI installed - which can also cause problems for rippers.
So the first thing you have to do is replace it ASPI - at least all the versions that are in the Windows directory tree with a full implementation.
Adaptec (the creators ASPI) do have an updated XP version (
4.71.2 is the current one) which they give away for free,
but I recommend that you NOT install it. Instead I strongly urge you to install 4.60 which works fine with XP and works with all the ASPI tools and utilities that I have encountered thus far.
The catch is that v4.60 is no longer available from Adaptec, but because it is so popular it can be found from a number of places on the net under the guise of "ForceASPI v1.7". Google for it, you will find it.
ForceASPI comes with a script (a batch file) that will find and delete all other copies of ASPI on your system, and a script that will install the ASPI drivers it comes with for you. A reboot will be needed.
Next you need to test that the new ASPI drivers are working. If you have Nero then start the Nero InfoTool and look at the version info on the ASPI tab. If you don't have Nero I recommend DirveInfo (search for "driveinfo11.exe" on Google), if all is OK then DirveInfo will give you the region info from your DVD drive, if everything is not OK it will give you an error.
Finally you should probably clean your registry out afterwards so that any lingering registry keys to old (now deleted) ASPI drivers are removed. There are a bunch of utilities that will do this (Norton has one for example) but I like an old tool that Microsoft created for Win95 called RegClean. Microsoft are no longer distributing it but you can still get it
from places like download.com
As for the actual DVD ripping software, well most people here are quite fond of SmartRipper, although personally I like
CloneAD but it really boils down to personal preference.