CRC clarifications

Hi,

I find that the polynomial for CRC-8-ATM is 1 + x + x^2 + x^8
and the corresponding representations as 0x07 or 0xE0
in the below link :-
http://en.wikipedia.org/wiki/Cyclic_redundancy_check

But, What does that 0x07 or 0xE0 refer to ?
Is there different algorithms for both 0x07 and 0xE0 ?

When and Where should we need to use 0x07 ?
When and Where should we need to use 0xE0 ?

Which is efficient ?

I find an online calculator for verifying the 0x07 -
http://www.usstmba.cn/chenjq/www2/software/crc/CRC_Javascript/CRC8calculation0b.htm

But, unable to find one online calculator for 0xE0 .
Can anyone provide me with an online calculator for verifying
0xE0 ? Any ideas ?

Thx in advans,
Karthik Balaguru
.