Ive been playing accustic (upright) bass for a while now but i have recently developed an interest in playing bass guitar. My rpivate teacher is discouraging this, however, because she thinks it will ruin my hand position for double bass...even though i already play guitar. And also...what kind of bass has the best sound for a rock/metal band?

I don't play upright, though, I plan on starting as soon as possible. Playing bass guitar won't hurt you in any way with upright; that is, if you practice enough upright. Bass guitar is much easier, since it has frets; and, of course, there are fretless bass guitars. If you can play both (guitar and upright), then you can become a very accomplished bassist--especially in jazz/funk/fusion bands. I'd say, go for it.

Check out Blue demon

www.myspace.com/bluedemon13 An unsigned liverpool band who use an upright bass. they're quite heavy too.

Nothing you do musically will hurt any other skills as long as you can apply what you know to each instrument. Since you have been playing upright for so long, and since it is much more technically and perceptively demanding, you will be able to apply what you already know to give a good twist to your bass guitar skills. And who knows, maybe you'll learn a bunch on bass guitar that you might be able to apply to upright bass.

I have a Peavey 5-string and I think it works well in any genre, depending how I play it; however, it's also very sturdy so I don't have to worry about hurting it when I rock out.

Rickenbacker 4003
cliff burton played it. Lemmy from motorhead played it.
it sounds amazing....and looks the best in my opinion, but it costs a fortune. id say ibanez basses. theyre pretty solid and sound good. and affordable.

it's great if you can play both.. of course the hand positions are different but it won't do anything bad really..

The lines are blurring between fretted/fretless and acoustic/electric. A lot of hybrid instruments are being introduced in the last couple of years. Fretless electric guitars are becoming more popular as well. Third bridge guitars are popular in avant-garde circles. The major difference is obviously the intonation factor. If you have good pitch - which you probably do already playing an upright - the transition will be simple. There are a lot of nuances to the upright bass as its naturally amplified. Electric bass guitars also have these but the amplification of instrument really changes its natural (unamplified) character (Check out Billy Sheehan's advanced DVD on this) What will be most noticeable is the pizzicato effect will be very different on a bass guitar. In the early days of electric basses, ala the Fender P-Bass. Leo Fender placed a cowl/cover over the bridge with little dampers over each string to simulate some of the character of the upright. Nowadays, most electric basses have done away with that but you can still probably rig something up to approximate it. There are a handful of luthiers who build electrics that have the character (and sound) of the uprights but they are very high priced. Typically in the several thousand dollar range.