build your own puter, it will save you tons of money, and you can add whatever you want, and they perform better for gaming(which is what i suspect you are going to do)
When Dell has its good deals, the price for a Dell system is less than the price of the individually bought parts. Thus you'd pay a lot more to build it yourself. Dell has also gotten rid of nearly all its proprietary parts (meaning that you get the same thing you'd get if you bought it yourself. The only remaining proprietary part is a motherboard that isn't overclockable. So as long as you aren't going to overclock, there is no difference at all between a Dell and something you could build on your own (no speed difference like you claimed).
I wanted to buy 2.53Ghz Dell 4550.
Today I don't see the 2.53Ghz option and the GeForce Ti 4200 video card.
This results in a higher price.
Is there a shortage of 2.53ghz P4 or Dell stopped offering?
Does Dell no more offers GeForce Ti 4200 video card?
Dell and other companies tend to go in cycles. At times there are tons of options and at other times there are very few options available. Generally around Christmas time Dell's staff is the most busy and it is also when the "less computer knowledgeable" people tend to buy. For both reasons Dell usually simplifies their choices (meaning they just recently cut complete computer lines, and there are fewer choices on each computer). I think this makes some sense when looking at it from Dell's point of view. I haven't heard anything about a shortage of 2.53 GHz chips, but I bet they were cut due to lack of demand. The 2.4 GHz chip was much better in the price/performance region (I myself recently bought a 2.4 GHz from Dell for that very reason - I would never pay 25% more for a chip that only offers 5% more speed).
As for the other parts of the computer, I usually suggest buying the minimum from Dell and upgrading yourself since Dell often overcharges for them. For example, Dell is charging $320 for the 9700 Radeon Pro when you can buy it yourself for $298 (shipping included). Or Dell is charging $60 for 128 MB extra of PC2700 DDR but you can get 256 MB extra installed yourself for $54. Thus if I were you I'd get the minimum video card, buy what you want online, and then sell that Dell video card for a profit on ebay. Same thing with memory.
Dell has been getting hundreds of complaints on their own forums about not having the 9700 Radeons and instead having the GeForce models. I guess when they simplified for the holiday season, they listened to those complaints.