Can be ... I tend to prefer a zoom just because it's easier to frame what you want. Maybe I'm just lazy! You can use pretty much anything for a 'landscape', it's just that with a longer zoom or prime you will get much less in the frame ... you'd get some land, but much less scape
You can also 'stitch' together several narrow frame shots in software to make one long landscape ... personally, I can't be bothered!
Of course, your kit lens is 18mm (I think!!) at the wide end and it might be worth seeing if the quality is up to scratch for you. I have never used mine so dunno. Seems to be mixed reviews, some like it and some don't.
The 17mm (x 1.6 crop factor, of course) is nice because you'll get a lot in, but then you may have to walk forward or back a bit to get the image framed as you'd like (or you could crop the image afterwards). With a zoom you can frame without walking around and so you are less likely to need to crop later (or as much).
First time I used my Tokina I found it was immediately apparent what an advantage a wide can be. You just get so much more in shot. I definitely welcomed the zoom, and I think I would miss it if I didn't have it now, but I'm sure I would have adapted to a prime as well. I just might not have used it as much or with such flexibility.
My Tokina is superb and VERY well reviewed. Because it's not seen as a 'cool' L lens you can pick them up at nicer prices ... less than £200 if you're very lucky: a bargain considering they normally sell at around the £450 mark new!
Check out the review section at fredmiranda and see if you can find anything decent in your price range ... then have a look on ebay. Never know ... that's how I got mine. Just luck. It was my first choice, along with the Canon 17-40 L which sells for silly money SH, and there it was on ebay. Fate
I had a 'wide and walkaround' shortlist that I typed up and if you want it I can see if I can find it and post later.