Celeron is fine if you're not into gaming/encoding/rendering. Basically it comes down to what the user actually needs. I would recommend Athlon XP in any situation over the Celeron, but sometimes a customer insists on Intel. All you can do is tell them the fact is that a Celeron 2.4Ghz is about the same as a 1500+ AMD in terms of real-world performance. A majority of users use their PCs for Web/Email/Music/Video/Small Office apps, all of which run fine with 1Ghz+ and a decent amount of ram. It's when the user wants to run apps that require more power (games/content creation) that it gets trickier to find an appropriate solution.

Socket 940 will have a respectable lifespan, certainly longer than that of Socket 754. Also, registered DDR is now only a fraction over the cost of ordinary DDR, at least for decent brands like Corsair. AMD has just released the Opteron x48 models, and it looks like there will be ramping on Socket 940 through 2.8ghz. This offers an upgrade path of actual 64-bit processors (and they are very reasonably priced compared to other 64-Bit processors. Socket 754 is going to be relegated to low-end 32-Bit solutions, and Socket 940 will remain as a workstation/server solution. Obviously the best choice for someone investing in 64-Bit would be Socket 939, but we have to wait a few more weeks for that option. Socket 940 is much better than socket 754, AMD made a huge blunder by releasing a single-channel interface for a high-end core.

As far as socket 754 being overpriced.. YES IT IS! You're using Intel's high-end pricing as an excuse, when in reality it's just the same. It's just as bad buying a P4 3.2Ghz at $320 as it is to spend $250+ on a 64/3200. Price/performance? The $90 2500+ with a decent heatsink/fan will hit 2.2Ghz(3200+) on a Nforce2 mobo. Combine with better components with the $160-$230 you just saved, and you are a big winner. Socket 462 is basically dead in upgrade path, but so is Socket 754 except for value parts. Socket 478 for Intel has a few things coming, but nothing that will last as long as the Socket 939/940, so it doesn't make sense to buy high-end P4 at this time. Although the best high-end solution is 2.4/2.6C overclocked to 3.4+Ghz. Very fast and much cheaper than AMD64. Still not as good a deal as 2500+ though.

Unless you are really bleeding $$$, stick with Barton XPs + Nforce2 until Socket 939 matures next spring. If you have to have high-end RIGHT NOW, get Socket 940+Opteron/FX. If you want a middle-ground solution, look at the low-end 800FSB P4s.