150watt hps light good?

Hello. so i was just wondering if this wouldn't be to little for my 5'x4'x8' closet when im ready to start flowering? And heat is always a problem. how much heat will this put off?

http://cgi.ebay.com/Sun-System-150-Watt-HPS-High-Pressure-Sodium-Grow-Light_W0QQitemZ180378373821QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item29ff638ebd&_trksid=p3286.c0.m14&_trkparms=65:12|66:2|39:1|72:1205|293:1|294:50

That looks like a very efficient grow light. It says it has a vented hood so that should be good as well so you shouldn't have heat problems.