"Chinese" vs "Mandarin"

Do you know when to use the word "Chinese" & when to use "Mandarin" ?

This may seem like a silly question but well, over my blog, I'm not ashamed to tell you - I DO NOT KNOW :P

So, over MSN, I posed Cosmic - the intellectual who is interested in anything Chinese, and has studied in China before - this question and well, below is a summary of his take on this. Do note that this is what Cosmic understands and he disclaims that it might not be fully accurate. So pls just read this with a pinch of salt and do not flame him if you think that his explanation isn't correct. Pls feel free to post a comment to share your understanding or your take on this (best is if you can substantiate your points as I am very much a factual person. Don't show me the $$, show me the cold hard facts. Guess this is the trait of a technical person. We believe in facts, not sentiments, not gut feel). Your efforts will be greatly appreciated and if/when I have nothing better to do (I count watching dust settle as one of the many tasks in my to-do list :P haha kidding lah), I will do some research on your comments and revert on my findings.

In what context do I use the word "Chinese" over "Mandarin"

1. "Chinese" can be used to refer to language, race or things associated with it, while "Mandarin" only can be used in association with the language
2. "Chinese" (the language) in Singaporean context refers to "华语"
3. "Chinese" (the language) in an international context refers to the official language of China, also known as "中文","中国话"or"普通话"
   
4. "新加坡华语" is virtually equivalent to China's "中文", the difference is tat "新加坡华语"contains a certain % of local terms borrowed from the various chinese dialects (esp. hokkien) and malay. Terms like "组屋" (flats), "电子公路收费系统" (ERP) are terms peculiar to singapore and are not present in china's "普通话"
   
5. "Mandarin" can also be used to refer to officials above a certain grade in the Qing dynasty. Mandarin refers to the official language used by the olden chinese official and imperial courts in the north
6. There is a tendency for Singaporeans to refer to the chinese language as "Mandarin"

Confused ? I know I am. So does it mean I can say "I speak Chinese" or "I speak Mandarin" ?
*scratch head*