I know this is a little off-topic, but:
Just a tip, as much as I love supporting my LFS, Every retail place i've been to charges up to twice as much for powerheads as most online stores. I try to buy as much as possible at my LFS, but for some reason powerheads seem to be way outside of realistic pricing in retail locations, and I draw the line at paying 200% for equipment. Many online stores have deals on shipping, so I wouldn't pay much more than $20 for a powerhead. That said, if you find a good deal, have the extra money to spend, or don't want to wait a couple of days, by all means buy it retail. As for most other equipment/supplies/etc., I prefer to pay a little extra now so that my LFS is still in business when I need advice (I have a really good LFS) and/or for when I need something in a hurry.
An underground filter is definetly not needed. The Maxi-Jet power heads that I favor come with excellent directions that even my completely non-mechanically inclined brain could figure out. Also, I don't know how big your tank is, but I like two (or more) smaller powerheads versus one larger one so as to create fewer "dead" areas in the tank where there is little water flow.