A second to that statement on English being the most spoken SECOND language in the world. I was taught that in a socio-linguistics class in the '80's.
The #1, or native language, based on population studies, is Chinese in all its dialects.
The Summer Institute for Linguistics (SIL) Ethnologue Survey (1999) lists the following as the top languages by population:
(number of native speakers in parentheses)
1. Chinese* (937,132,000)
2. Spanish (332,000,000)
3. English (322,000,000)
4. Bengali (189,000,000)
5. Hindi/Urdu (182,000,000)
6. Arabic* (174,950,000)
7. Portuguese (170,000,000)
8. Russian (170,000,000)
9. Japanese (125,000,000)
10. German (98,000,000)
11. French* (79,572,000)
* The totals given for Chinese, Arabic, and French include more than one SIL variety. (1)
Slightly different on Wikipedia. They give two cross-indexed references. One that just lists by rank with no figures given (2) and one that gives comparative listings with figures from different sources. (3)
No matter which source is used, though, Chinese comes out on top.