...the bios setup to recognize the pentium 3 processor? I have a compaq deskpro sb, i bought it from a former employer. I have been doing some upgrades to it. Ive added more memory, a dvd rom, bigger hard drive. But it only had a pentium 2. Well i got a pentium 3 that was out of a hp vectra. Its the same style and fits in the slot perfectly. I can load windows 98 se with it, but for some reason it will not load windows xp. i cannot figure why it would load one operating system but not another. If anyone can help me i would greatly appreciate it. I dont have enough money to buy a new computer so i just do what i can with what i have.thats what i have. i work at a local community college at i got a cd of xp pro.i have xp pro. and believe it or not it worked on the old pentium 2.