Getting re-Set-up For XML Development – After A Two Year Hiatus

Hey guys – I could use your help regarding the best XML Editors and Parsers as of late. Right now, I need an XML Editor with an XSLT parser — and preferably an XML Schema validator, built in.
I’m also interested in php modules for XSLT.
And for XSLT tutorials — so I can ramp back up!
Thanks in advance for your usual great advice.
lisa