I am currently using a 27' 2.7ghz imac with 8gb ram. I recently upgraded to Lion, and while I haven't experienced any problems with it thus far, I did notice that my boot and shut-down timings do seem a tad slower. It may be my paranoia, but some programs like ms office do seem a bit more sluggish in opening as well. As such, I am wondering if there are any benefits to doing a fresh install from a USB, and how I would determine if my imac needs it or not? I am not really very tech-savvy with this sort of thing. Also, I am aware that programs like iphoto won't automatically get reinstalled. Do I need to download them again from app store, and if so, do I need to pay any extra charges? Would really appreciate if you all could walk me through this. Thanks in advance for your assistance in this matter.