So, your question faces two physical problems, even given your assumptions:

- The energy requirements to move a planet; and
- The time it takes to get to other planets.

I'll address the former for now.

I found a number online that says how much uranium we mine every year. This number is not accurate (no unclassified number would be!), but I'm going to use it anyway: `50 Gg` (giga-grams; or mega-kilograms; how's that for a unit?).

So, let's say this number represents your quantity of uranium for the fuel (to use for the reactor). I'm also assuming the 90% UTB from the linked page. Note that this is an over-estimate because there will be losses and you'll never achieve this, but it'll help this problem.

With that fuel, the 90% UTB reactor can thrust for `1633986.928 seconds` (or `18.9 days`) on one-year's worth of mined uranium.

Burning for that long with the specs in the link provides `5e19 J` of kinetic energy (theoretically). Note that this is also an overestimate because losses will occur.

So, using the 1/2*m*v^2=energy equation and the mass of the earth (thanks, Wolframalpha), this translates into a whopping...

...wait for it...

**4.313 mm/s change in velocity!**

Woo!

According to another link I found (which is right up your alley! and is pasted below...), the escape-velocity from the sun's gravitational field in the vicinity of earth is...

...wait for it...

**42 km/s**

You'd have to be 10,000,000 more productive than we currently are to reach escape velocity.

In terms of joules, it requires `4.457e32 J` for earth to escape.

Nuclear fission is particularly good at turning mass into energy (`E=mc^2` and all that), but it's still not really good at it. However, if you assume you instead have an engine that **IS** perfectly good at this, and you were to convert a year's worth of uranium into pure energy to propel earth, you'd get a whopping...

...wait for it...

**4.949e24 J**

So it would still take almost 100,000,000 more energy than that to get earth to escape velocity.

So no, it is not particularly realistic to move earth to travel between star systems.

But here's the link, which you'll want for some light reading: http://www.quora.com/How-much-energy-would-it-take-to-shift-the-Earth-from-its-orbit-around-the-Sun-and-propel-it-out-of-the-solar-system-and-are-there-any-processes-natural-or-otherwise-that-could-achieve-this

*(Also, that's a ridiculously long link.)*

One final note: it's amazing how many of these numbers are awfully close to starting with a 5...