Okay, let me give an alternate opinion.
Arial is the plain vanilla of fonts. In your design, you don't want to stray too far afield from the cool, minimalist, "Danish Modern" :lol: feel it imparts in its use (this has all been said, and more, about Arial's older sibling Helvetica), but there's no reason you can't work with it in a slightly more varied fashion. There's nothing wrong with using a similar-but-different sans-serif font (say, Lucida Sans or Segoe UI, maybe even Tahoma) or a boldly different serif font that still imparts that cool, minimalist look and feel. A fantasy font, say, or a slab serif would not work at all with the Arial logo.
What Arial is doing, like any font, is setting a tone. Stick with that tone in your font choices, whether you go for strict similarity or something quite different.