Share your experience!
You can find and download detailed Xperia X10 user guide from the following link
http://www.sonyericsson.com/cws/support/phones/detailed/userguide/xperiax10?cc=gb&lc=en
is this the instructions for using android 2.1 and the UI upgrade. if not, then i done this when i got the phone, and hardly worth while when the software is about (maybe) to be upgraded.