Hardware-oriented
There were questions over the extent to which Apple would retain control over the non-processor components of the system design. Apple is traditionally a systems builder, and some feared that Apple's industrial design philosophy may be affected if the company switched to commodity parts. Others noted that Apple has slowly been switching to standard parts since the introduction of the PCI Power Mac in 1995, and said that using a non-Apple chipset in itself would not harm the Mac's image.
Intel Macs employ a different Intel technology for firmware, Extensible Firmware Interface, not the Open Firmware Apple had been using. EFI removes the traditional PC reliance on the BIOS while providing more functionality.
The use of the x86 architecture allows Windows to run natively on Apple hardware, and opens the possibility of using the Wine package to run Windows executables directly. Some fear that the change will make Mac OS X a less valuable target for software developers, since Mac OS X users can use a dual-boot setup or a Wine variant (such as CrossOver Mac or Darwine) to run Windows apps instead. Others say that it could be a boon to switchers, since they would not have to leave their Windows applications behind while trying out Mac OS X. The idea of Mac OS X being available on regular PCs has also been discussed, but Apple has said that they will not allow regular PCs to run Mac OS X. The OSx86 Project, however, is able to install Mac OS X on non-Apple PCs. It was previously thought that since Windows XP is incompatible with the Extensible Firmware Interface, it would not be run on Intel-based Macs. Prior to the Boot Camp announcement, a prize contest resulted in a working solution for dual-booting Windows XP and Mac OS X on an Intel Mac. Microsoft has announced that Windows Vista will not be EFI-compatible on 32-bit platforms, but the latest versions of Boot Camp allow Vista to be installed on any Intel Mac.
Intel was seen among the Mac community as a purveyor of hot-running chips (especially the Pentium 4). Apple themselves mocked the Pentium range in their "Toasted Bunnies" advertisements of the late 1990s. However, the Pentium M chips, which were designed for laptop use, run much cooler than the Pentium 4. Apple claimed the then-new Intel Core chips, which are based on the Pentium M microarchitecture, would have dramatically better performance per watt than the PowerPC G4 and G5.
Finally, the relative quality of the x86 architecture has been discussed. Critics of the switch say that x86 was a poor choice because of its lack of hardware registers compared to the PowerPC, and the lack of AltiVec (also known as Velocity Engine). Proponents have responded by saying that the x86 architecture has evolved greatly since the original 8086 was introduced, and that CPUs in general have combined RISC and CISC philosophies in their internal designs for some time, making the distinction obsolete. They also point out that improved SSE could equal AltiVec, and that most programmers rarely deal with x86's peculiarities because the compiler does the work.
The Core Solo and Core Duo chips are 32-bit designs. On August 7, 2006, Apple released the Mac Pro and Intel-based Xserve, introducing Intel 64 (Intel's implementation of x86-64) architecture into the lineup through the use of the Xeon processor. As of August 7, 2007, all other computers in Apple's product line have been updated with the 64-bit Core 2 Duo.
While the current benchmarks comparing Core Duo to Core 2 Duo processors show very little difference when running in 32 bit, the 64 bit edge has become more of an issue with the release of Mac OS X v10.6 (Snow Leopard), and now users can dual boot Windows 7 in full 64-bit mode.
Read more about this topic: Apple's Transition To Intel Processors, Hurdles Associated With The Move