None of your specs matter. HP used two different size power supplies in recent years, SFX and PS-III. PS-III looks like standard ATX supplies (which are PS-II size) from the back, but have a shorter lengthe. SFX is tiny in comparison. You can see pictures of them <A HREF="http://www.chieftec.com/products/psu/PSIII & SFX PSU.htm" target="_new">HERE</A>.
Now I've showed you what they are and what they look like, but somebody will still call one or the other a "micro ATX" power supply, because people in here are hard headed and do not listen! The fact that venders don't even know what they are selling doesn't help! Examples are:
1.) <A HREF="http://www.newegg.com/app/viewProduct.asp?description=17-104-980&depa=1" target="_new">An FSP brand PS-III power supply for $20 at Newegg</A>
2.) <A HREF="http://www.newegg.com/app/viewProduct.asp?description=17-104-981&depa=1" target="_new">An FSP brand SFX power supply for $21 at Newegg</A>
Notice that even Newegg is stupid enough to call both of these supplies "Micro ATX" even though they are different form factors! There is no "Micro ATX" nor "Mini ATX" form factor for power supplies, there are SFX and PS-III!
<font color=blue>Watts mean squat if you don't have quality!</font color=blue>