So I'm in the market for a laptop. There are two that I'm looking at, with the following specs:

Intel Centrino 1.6GHZ 2MB L2 cache
512MB ram / 60GB HDD
15.4 inch widescreen
Single layer DVD burner

Intel Celeron-m 1.3Ghz 1MB l2 cache
512MB ram / 60GB HDD
15.4 inch widescreen
Dual-layer DVD burner

The celeron is about $200 cheaper, but I'm weary because I know that celerons are slower processors than their Pentium counterparts. The reason I'm worried is because I don't want it to become obsolete too quickly.

Is the celeron still a good laptop or is the Centrino a dead winner?

All advice appreciated.

Centrino describes not the processor but a package of components that includes the pentium-m processor and other wireless technology. It is a marketing label.
Worrying about PCs becoming obsolete too quickly is pointless. In 6 weeks anything you buy will be superceded. In 12 months it will be obsolete. Forget the jargon and buy whichever unit will meet your current and anticipated needs for a period of two years. The main difference in the two is the L2 cache. I'm not sure exactly what that means in day to day operating terms. You will need to do some research on that to determine if the difference is worth the $200. The fact that one comes with dual layer DVD and the other only single layer is almost irrelevant unless you are into burning long movies. Dual layer media is still 10x more expensive than single layer so most people will not use the dual layer functionality at all before the thing is worn out. laptops by their nature have only limited upgrade capacity so just buy the one that best suits your particular requirements. I met a businessman yesterday who happily uses a 9 year old laptop running Win95 for his onsite work. It does the job he requires and you wouldn't pay $100 for it today.

Give a man a fish and you feed him for a day.
Teach him to fish and his wife will never forgive you.

From what I've seen of two laptops that are Centrino equipped, I think the $200 is worth it.

The wireless technology that it does and will allow may have "work arounds" with the other computer but they may be expensive or, not available.

goood thing to remember about the centrino is that the battery life will be 4hrs. the celeron will only give you about half that