OP, at 150K miles, I'd say toss another $150 radiator in there too...Behr is a good name.
Stay with OE components, especially for the therm and ET...if your belts look new, they may be...make sure they go back on the same way (note which way the lettering is and put them both back in the same direction).
Spin your pulleys...if free spinning, replace them--that's the two tensioner and 1 idler pulleys--make sure you know which tensioner type you have...hydraulic or mechanical as they require different pulleys--search 'pulleys' in thread title for help on that...very easy work...another 15-20 mins.
Yes, read Mango's thread...and read a few cooling system diys beyond that. Read until you feel a cold chill in your body. That's how you know you're ready! LOL
(Thanks for the props, guys...not sure what I said so well, but glad you appreciated it!)
Upcoming NYC dates: Jan 8 and 27. See Facebook for other shows and PM me if you can make one...love to see you there!
Mangofy your E46!