There are a variety of reasons why this is a terrible strategy, not the least of which being that you only make $100 for every $1 your stock goes up, but the main reason why is you are playing with a variety of factors of risk.

If you have $1000 and you buy 100 shares of an $80 stock and 100 shares of a $20 stock, you have WAY more at risk in stock 1 than you do in stock 2.  What you want to do is decide the amount of money you want to invest in a specific company is and then divide by the share price.

So, if you want to invest $1500 in a stock that is $12.37 you do the math and find out that it's 121 shares you should be buying in that stock.

Now, don't go putting 10% into every stock either.  That will just water down your investments.  You want to put more in the companies that are running (going up) so that you can take the profits out and get more shares for the future.  I have about 40% of my investments currently in Apple ($AAPL) and I'm killing it.  I should have more cash in it, but I like my long-term positions in the other stocks I have and don't want to take a tax hit right now.

In any event, don't buy 100 shares or in blocks of 100, look at the percentage of your investment portfolio you are willing to invest in a company and use that dollar amount to decide how many shares to purchase.

Invest in peace...