Kaufman Bros. analyst Shaw Wu wrote a note to his clients on Monday explaining why he thinks Apple is holding off the release of new iMac models.

“We wanted to give an update on the Mac business from what we are picking up from our latest supply chain checks,” Wu wrote in his Monday note. “While new the iMac appears to be almost ready for primetime, what is holding it up appears to be business reasons and a potential small technical hurdle ... Apple is in the midst of figuring out whether to power the new iMac line with Intel quad-core processors or more high-powered dual-core processors with larger caches,” Wu continued.

The analyst reasons that, if Apple chose Intel’s recently-released quad-core processors, the move “could cannibalize the Mac Pro.” A Digitimes report also suggests Apple is waiting on Intel’s new quad-core to release upgrades. However, Wu may be barking up the wrong tree, other reports have showed, with AppleInsider pointing out to Apple's currently acting CEO Tim Cook last week who said that desktop sales were “primarily iMac.”

Wu further tries to put his finger on the reasons for the delay, noting that Apple may want to roll out new iMac models along with the latest iteration of Mac OS X, version 10.6, aka Snow Leopard. Snow Leopard “takes [the iMac] to the next level” with enhanced chip and graphics support, Wu wrote.

Also a possibility for the delay, Wu believes, may be that Apple is redesigning the iMacs' cases, to fit new cooling technology needed for multiple-core processors that generate large amounts of heat.

If the 13-inch White MacBook is any indication, Apple is undoubtedly upgrading its iMac line soon. Apple has secretly beefed up its low-end notebook with a 2.0 GHz Core 2 Duo (1066MHz frontside bus) processor, double the original memory and better graphics, keeping the ports intact. The notebook can be acquired for the same $999 price as before.