You *should* not.  As with any operating system upgrade, things can go wrong and
data loss is a possibility, so there is always a chance that any program will have a
problem.  That's why it's a good idea to use the setup option to save the old
operating system as a backup, in case the upgrade is not entirely successful....then
you can always revert and try again.

Assuming the version of PowerDVD that you have is compatible with WinXP, it should
survive the upgrade as well as any other compatible program.  If it does not, you
can always uninstall it in XP and then re-install it from your PowerDVD disc.

My own experiences with upgrading form 98 to XP are that the following will
NOT work, unless patched (if possible) or replaced:

1.  antivirus (even if XP-compatible, you must uninstall under 98, upgrade
to XP, then re-install under XP
2.  system-like utilities (e.g., Norton)
3.  CD/DVD burning software (Easy CD Creator 6 has a patch, version 5 does
not, version 7 and later were made for XP).  Even if XP-compatible, it is
best to uninstall under 98, then re-install under XP.
4.  DVD players  (most built for 98 will not work under XP)

If your version of Power DVD does not work under XP, and if no patch is
available, try one of the free DVD players now available under XP, such as
http://www.avsmedia.com/DVDPlayer/

Other free or cheap software, mostly XP-compatible, is listed at Major
Geeks.  Look on left side of main page, under multimedia for CD and DVD
programs:

http://www.majorgeeks.com/

Additionally, you might want to run the free Microsoft Upgrade Advisor,
which will look for other incompatible software and hardware.  For example,
it warned me that I would have trouble with Outlook (from Office 97), and it
was right, so I now use the Outlook Express that came with XP.  But, the
rest of Office 97 works OK, so long as SP-2 for Office 97 is applied.

Link to MS Advisor:
http://www.microsoft.com/windowsxp/pro/upgrading/advisor.mspx