If you want to invest for medium to long term you need to research coins that have unique features (not Bitcoin/Litecoin clones). You also need to beware of scamcoins which are either premined or instamined. And keep in mind if Bitcoin goes down, altcoins will follow.

From $2000 I would put:

$350 into Litecoin
$350 into Peercoin
$350 into Namecoin
$350 into Stablecoin
$600 into Bitcoin

They all have unique features and strong communities behind them. Make sure you never invest more than you can afford to lose!