It looks like Google is back on track to be that $1,000 stock.

Having been in the $400 doldrums since February 22, it crashed through $500 and clear into the $520s, up over 75 bucks in after-hours trading Thursday on the strength of its over-the-top Q1 results and the fact that its US paid-clicks were up 20% year-over-year.

ComScore had given everyone a big scare on Wednesday when it said that Google’s paid-clicks in the US, the source of its fortune, showed weak, almost imperceptible growth for the third month in a row and were up just 1.8% for the whole first quarter, a nasty, nasty drop from the 45% Google reported in the third quarter of last year or even its 30% growth in the fourth quarter.

Of course, ComScore, whose credibility is now on the line, only counts American Google search ads, not its AdSense business with non-Google sites and certainly no non-US business.

And Google has fiddled with its click trying to improve their quality and hence bring in more money.

Anyway, Google’s Q1 earnings were up 30% to $1.31 billion, or $4.12 a share, on revenues of $3.7 billion – exclusive of the commissions paid to partners – up 46%, numbers that were better than Wall Street expected and perhaps a harbinger of better-than-expected results from Yahoo in a few days.

Google got 51% of its revenues in Q1 from outside the US.

The weak dollar contributed $202 million in revenue, Google said, and an unusually low tax rate contributed an estimated 23 cents to earnings.

But Google CEO Eric Schmidt still claims to be insulated from the US slowdown.

“It’s clear we are well positioned for 2008 and beyond, regardless of the business environment we are surrounded by,” he said during a conference call.