Hahahaha! Uh....
The truth is, that no processor is of higher quality. If the processor, on it's native platform (I.E. AMD760 for AMD or i850/i845) has any problems with crashing, it's of poor quality because it will crash when there are no external problems. I've never seen an AMD processor crash on an AMD chipset, neither have I seen a pentium 4 crash on an i850E system that was related to the chipset. (I've seen my i850 system crash more times than I can count, most due to harddrive corruption of some sort). The problem is that it's incredibly hard to "Prove" the "Quality" of the processor. WTF? What the hell do they mean by "Quality"?! If it runs, it runs. If it crashes, it doesn't run. If it runs, it's high quality.
I would challange your friends to a contest. Stick an AMD processor in a KG7-RAID and put in 256MB of crucial DDRSDRAM and let it run Prime95 for 2 weeks. If it crashes, AMD processors are of poor quality. Then let them try that on an intel processor. If it crashes, it's of poor quality. I'd be suprised if either processor crashed on their native platforms!
Now, on the physical side of things, the Thunderbird is of inferior *build* quality to the pentium4 (I.E. Easy to crack, easy to fry, easy to damage. After all, it's on ceramic packaging). The AthlonXP is a vastly superior CPU in physical build quality. I still say the highest quality CPU's that ever came out of AMD was the Slot1 Athlon. You could literally drop it on the floor and step on it and it would come out OK. But the AthlonXP is a close runners up (You can still drop it and expect it not to suffer excessive damage) and the throughbread should be equal to the AthlonXP.
Now, I will state this now. The Thunderbird packaging is of completly inferior build quality compared to the Pentium4. Does that matter? Not necescarily, but I would dare you to let a noob install an Athlon heatsink and see if he manages to screw things up. Then I dare you to let a noob install a Pentium4 heatsink and see if he can mess things up. (I guarantee you, 9 times out of 10, the Pentium4 will survive more noob instillations than the Thunderbird. 7 times out of 10, the Pentium4 will survive more noob installiations than the AthlonXP.)
The only way to convince them the Athlon is of good quallity is to take a good stable motherboard like the KG7 and a well cooled AthlonXP and let it run prime 95 for a month or so, and see if it crashes. Then let them try that feat on a P4X266 heh heh... no just kidding. Let them try that feat on an i850 motherboard, and see if it'll crash. Neither should, really. Unless ofcourse, you drop one system, then they'll both crash.
At any rate, the only way a processor should be of better quality than the other is it's physical build quality, and in that position the Thunderbird/AthlonXP/Throughbred have always been of slightly inferior build quality when compared to the Pentium4. When we're talking about chipping cores and frying things and such, the AthlonXP has a natrual disadvantage. It's buck naked.