I do not know a lot about wireless but found this on the Intel Q&A page.
Seems to answer why Centrino is better than Celeron.
http://www.intel.com/products/processor/index. htm
Q)
If Intel Celeron M processors and Intel Centrino mobile technology are both part of Intel's mobility family, what are the differences?
A)
Intel Centrino mobile technology represents a combination of Intel's best mobile technologies (Intel Pentium M processor, Intel 855 chipset family or Intel 915 chipset family, and Intel PRO/Wireless 2100, 2200BG, or 2915ABG network connection) delivering all four vectors of mobility: performance, integrated wireless, enables great battery life, enables thinner/lighter form factors.
The Intel Celeron M brand represents only the Intel Celeron M processor. Designed for mobility, the Intel Celeron M processor delivers exceptional value with a
balance of mobile processor technology enabling thinner and lighter systems.