From my perspective, x86 chips didn't actually get "good" until 4 or 5 years ago. Before that, they were power-sucking, hot, and inefficient across the entire range. AMD was a bit better than Intel, but PPC seemed to offer better performance per clock cycle while using the least electricity.
Now, however, x86 has strong multicore architecture and a good product range that encompasses the powerful and the power-efficient.
Whether this is due to a business relationship with Apple is impossible to say, but I think Apple's decision to switch has been fully vindicated.
(Which does make me a tiny bit sad because I do have a soft spot for PPC)
AMD K8 Athlon 64 Mobile(1) in 2004 says Hi. IBM CPC 925's(PowerPC 970's NB) alone has a TDP of 30 watts. AMD K8 Athlon 64 Mobile has a 35 watt version i.e. "Odessa" (CG, 130 nm, 35W TDP(2)) up to 2Ghz.
1. At that time, I used Mitec 8355 laptop with Athlon 64 Mobile and ATI Mobility Radeon 9600 Pro.
2. Max power not typical power.
A 2GHz 970FX(90nm) consumes 39 watts maximum.
http://www-306.ibm.com/chips/techlib/techlib.nsf/techdocs/9DBF300EB19A60D287256E4B005E43EC/$file/970fx_thermal_an_7_20_05.pdf
Dated 2005.
By the time of 90nm for AMD, Turion MT-40 at 2.2Ghz has 25 watt version. Turion MT was first release around March 10, 2005.