Apple had reasons for ditching PowerPC in favor of Intel’s x86. But Apple is taking a big chance with the future of the Macintosh and might be giving up more than it’s gaining.

The main reason Apple switched was to acquire faster processors. In particular, Apple is hurting for a low-power processor competitive with Intel’s Pentium M, at a time when about half of all computers sold are notebooks.

Apple probably won’t save money by switching, and Macs probably won’t get cheaper. My sources say Apple pays about $100 per PowerPC chip. Intel’s average price is closer to $200. Theoretically, Apple can make up the difference by leveraging commodity-priced x86 chipsets and motherboards—or can it? Apple says x86 Macs will continue to be proprietary, which could mean some components won’t be commodity products.

Understand that when Apple releases the x86 version of Mac OS X, you won’t be able to buy a copy and install it on your Wintel PC. Apple says Mac OS will run only on x86 systems from Apple. To keep hackers from subverting this strategy, Apple must rig Mac OS with super-strong protection, which almost certainly requires a hardware-software security solution—the equivalent of a built-in dongle. Will x86 Macs have special chipsets or motherboards? Maybe, but I think Apple will use Intel’s LaGrande security technology to keep the Mac proprietary.

If Apple is using LaGrande, it might explain why the first x86 Macs won’t arrive for a year, and the full transition will take even longer. Apple is probably waiting for LaGrande to ship and also needs time to cripple Mac OS so it won’t run on other x86 PCs.

Meanwhile, sales of obsolete PowerPC Macs are sure to decline, and some software developers will balk at porting their programs to x86. Many developers just finished porting to OS X from OS 9. Although millions of Mac users still use OS 9 to run legacy software, Apple says the x86 Macs won’t run the older operating systems or any software written for the original 68000-based Macs, so the new platform will leave a great deal of software behind.

Most people resist buying Macs because they’re more expensive and run less software, not because they fear Macs have slower processors. Apple’s switch to x86 won’t remove either obstacle.