Just because your friend bombed out doesnt mean u will. Its not about the watts, its about the lumens and how you use them.
Mylar is a good but Panda plastic is better IMO, it reflects light really well, its easy to clean, apposed to scratching up your mylar, and it wont let light escape or tear.
Your working in basically a 3x2.5 area, this is not alot of space, how many do u plan on growing at once?
In my opinion, i wish i would of had someone tell me this when i built my closet the first go around.. Get a grow tent, proper ventelation, then worry about your lighting. Dont cut corners, and do your research before you choose lighting, T5's and CFL's can do the same as a MH or HPS, its all about strategy man. You can make a few CFL's work to your advantage depending on how creative you are.
Good luck