Convert Inventor 2011 files

We normally use Inventor, R2011, but we have a client we've done a major project for who uses SW probably R2013.  We did the engineering and design and sent it to them in .stp format.  Now they want us to quote a drawings package.  Is it possible to convert drawings (and associated models) from Iv R2011 to SW R2013?  We have 2 seats of SW R2010 which we could use, but we only have one full-time drafter who knows SolidWorks.  We're concerned we can't meet the time frame.  Also, I read that SW R2013 is not Windows XP compatible.  Is that true?  Thanx for your help.