FSB has nothing to do with multi-tasking. FSB is the rate of speed between the CPU and northbridge.
Longer lasting is irrelevant. Any CPU will far outlast its own technology if handled right and not overclocked.
like I said, read the article. The XP is a superior chip for the same amount of money.
L1 and L2 refer the the memory the CPU has built into itself as a buffer for the transfer of data to main memory via northbridge. Northbidge is a hub of circuits that connect to main memory and some components.
Southbridge is another pair of components hubbed (on the motherboard)
Just go with an XP if it is offered with a laptop. If you're a gamer, don't bother with a laptop. Laptops by nature are usually slower than desktops and are primarily devoted to running applications while on the go.
Just a note - DON'T confuse the Sempron with the Sempron 64 (these are two different chips.) The Athlon XP (32 bit) is superior to the Sempron (32bit), the Athlon 64 is superior to the Sempron 64.
Basically the Sempron in both cases is a stripped down Athlon.
Yes there are gaming laptops, but it isn't worth the cost and you can't upgrade critical gaming components on a laptop like graphics cards.
Multi-tasking/ multithreading refers to a CPU's capability of handling more than one instruction set at the same time by optimizing clock cycles. Neither the XP nor the Sempron multi-task. They are linear CPUs. Only far more expensive chips do this. Furthermore you must have a program that can instruct a multi-tasking/threading CPU to do so. Very few programs do - mostly applications like databasing. For the most part, multi-tasking/threading is a waste of time for the average user, he will never or seldom use it.
What determines a CPUs speed is a lot of factors, but mostly it's clock cycle TIMES it's Front side bus speed. This is why AMD chips are rated at 2200+, 3200+, for example. When compared to an Intel processor of the same class, a 2800+ AMD chip runs approximately at 2800 megaherz or better when compared to the same class of Intel chip.
You CANNOT compare speed ratings of CPUs in different classes from the same manufactuer, for example a 2800+ sempron versus a 2800+ XP CPU.
The XP series CPU provides the best bang for the budget buck at the moment USING 32 bit technology.
If you have more money go for the AMD 64 series CPUs, the X2 series, or the FX series. These are 64 bit chips that can run 32 bit. However, there is not a whole lot of support for 64 bit software yet, and for the most part, these chips are under-utilized and ahead of their time as well as very expensive.