A stationary bike like the Giant, or a Lemond, is an excellent choice -- I'd love to have one. They offer lots and lots of advantages, as far as I'm concerned, particularly if you own one, and can carefully dial the positioning.
Which you can, with these things. A modern stationary bike from a reputable maker allows for most of the adjustments you need: saddle up/down, saddle fore/aft (in a huge sweep, generally -- inches and inches), and the same for the handlebar assembly. In essence, you can recreate the BB/handlebar/saddle relationship of your bike with reasonable accuracy.
Some allow for saddle changes (not sure about the Tempo).
Riding your own bike in a rear-wheel trainer is a great alternative to owning a dedicated stationary, but let's face it... it's a bit clumsy and falls short in the comparison. Going out of saddle, and even hard flat spinning, can be treacherous; the stability of the unit relies completely on a fixed, unflexing clamp on your rear-wheel skewer. Riding naturally, particularly if you're going hard, depends on the bike swaying with your cadence -- not possible in a trainer. With each stroke, the whole frame twists, sometimes noticably. Rear tire wear can be considerable, too.
Don't get me wrong... in the end, I love my fluid rear-wheel trainer. I'd just never use it if I had an adequate stationary bike. Go for it!
