If I opened up my Xbox 360 console, can I still send it to microsoft for repairs?

No, since u voided the warranty they will not repair it, However if you're someone like me who opens there 360's and knows how to fix them it shouldn't be a problem. Plus even if the warranty was still good, it would take about a month before u got ur xbox back, So find out what brand ur disk drive is, and u can find replacement ones on amazon and ebay that are pretty cheap. Please note that the replacement drive has to be the same brand as the one that came with the xbox, always it won't work. Good Luck!