Trouble with incd and nero cd speed

Hi all, just a couple of questions i have win xp and win 98se on my system have just flashed my liton 32/12/40 to a 40/12/5s using the XSU1 firmware, first question under win xp when i run nero cd speed i get error messages no matter what test i do , yet under 98se ,no such errors try to format with incd in xp end up with error 000@-0002-00004-0004 yet no problems in 98 this is quite frustrating as my main os is xp .Also after burning audio, x 40x there seems to be quite a few errors on my 40x speed rated cdrs like lots of pops and clicks and some cdr,s wont even play or play some songs and then stop is this normal for this speed or should i just burn at 16x and be safe .whats the use of having a fast burner if all it does is burn fuked cd,s your help is much appreciated