Dividends are considered regular income and are taxed at your marginal income tax rate. Selling a stock that has gone down in value is called realizing a capital loss. Capital losses primarily offset capital gains; however, you can also use capital losses to offset up to $3000 of regular income. Since your dividends are less than $3000 you could sell stock at a loss to offset your tax requirement.
The question, though, is whether this is worth it. If you don't want to hold your GE shares anyway, then sure you can sell them to harvest the capital loss. But if you'd otherwise hold them, it's unlikely to be worth it to sell them just to save $100-200 of taxes.
The amount you'd have to sell to cover the taxes depends on what the stock was worth when you bought it. To figure it out, divide your $640 of dividends by the difference between the current price and the price you purchased the stock at (in dollars). So if the price of one share of GE stock went down by $20 since the time you bought it, you'd have to sell 32 shares to offset your dividends.
I didn't originally realize that $200 of these dividends are in an IRA. You are not taxed on dividends in an IRA. Instead, you pay tax on your income when you withdraw from the IRA (assuming it's a traditional IRA). So this year you would only be taxed on about $445 of dividends.