Though Monday will be the last day Microsoft sells XP or provides free support for the “hundreds of thousands” of computers that are estimated to run on it, the company has come up with a novel way to wring money from the aging operating system: It is killing XP but isn’t letting it die. One way Microsoft will still make money from XP is by charging to provide support. Because the software continues to be popular, Microsoft’s “extended” support program is sure to generate lots more revenue. Microsoft will offer the program at least through 2014. That will likely attract lots of big corporate customers. Meanwhile, Microsoft will make more money by supplying XP to computer makers Hewlett-Packard Co., Dell Inc. and others. Because Vista has had trouble making headway in the corporate market, computer makers have asked for “downgrade rights” - the right to continue offering XP on their notebook and desktop computers after.