i would highly reccommend just upgrading your processor to a phenom 955 or a phenom 980, you have a perfectly good rig right there, and upgrading to an SSD. you would not notice a difference in gaming beetween a 1100T and a 955.
you mobo supports up to the phenom 980, so unless you want to waste your cash i would highly reccommend sticking with your current rig:http://bizsupport1.austin.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c01925486
an SSD, would give you that speed difference you are looking for. and that GTX 570 should be able to play almost any game today at ultra settings even at 1080p.
imo if you have cash to burn then upgrade to the setup you listed, otherwise just upgrade to a phenom 955 (or a phenom 980), and buy an SSD, and enjoy!