Speaking from experience, the short answer is no. Photoshop 7 actually shipped in only one version that worked with both OS9 and OS X. Thus, it was built on Apple's older language, Carbon. Up until OS X 10.4, Carbon programs could still run natively. However, with 10.5, Carbon support was greatly lessened, and Classic Mode was entirely obliterated. Photoshop 7 relies on many of the functionalities that are not found in 10.5 onwards, so you're pretty well stuck.
If you're committed to running version 7, you might want to see if you can get a cheap iMac that will run 10.4, as Ps 7 will run like a champ under that. I also own Ps 7, and I have found that to be my only choice.