If style XP is set not to use any ressource (ie not loading on the boot), then it is no more an issue than the xp styles (blue, white and green) - such is not the case with windowblinds. With all the ls themes I used, I never had any problem of compatibility between StyleXP and LS (but I never used nonstep), except for the fitting of both looks. Anyway, to use a classic Windows theme is always better...
:)