In doing some reading, one of the popular CPU swaps for the 1,1 seems to be to change out the original 5150s(2.66ghz dual core) for 5335s(2.0ghz Quad Core). I have a couple of IBM rackmounts gathering dust, so have a matched pair of 5335s readily at my disposal. Looking at the spec sheet and comparing the 5150s to the 5335s, it looks like I get double the L2(8mb vs 4mb) although I would presume that this is related to the fact that it's also double the number of cores. Of course, that comes at a loss of clock speed. For the most part, I don't do a lot of "heavy lifting" with my 1,1-its mostly used for word processing/Excel and web browsing. I do use Adobe Lightroom a fair bit, though, which is where I seem to notice the most bottleneck and lag(the adjustments/sliders aren't as instantaneous as they are on my MBP), so would do the swap if I would see the benefit in this particular application. I suppose that-in the worst case-I could just do the swap and evaluate it myself since I already have the processors on hand. On the other hand, from what I've seen the 5300 series processors seem to be dirt cheap across the board now. In my searching, I haven't found any specific references to quad-core processors that are close to or faster than 2.66ghz. That would seem to be ideal since(theoretically) I shouldn't see any loss in performance for the single-threaded applications I use frequently but would also get the benefit of more cores for multi-threaded applications. I'm assuming that LR could take advantage of more cores. Can anyone who has done this exact swap(5150 to 5335) comment on it? In addition, could anyone suggest a quad-core that will at least come close to 2.66 and work without too much trouble?