Does anyone have any ideas on what the best investment would be? I have invested in a mutual fund index 500 through vanguard.
Impossible to say without knowing much more about you: your age, your income, the amount you have available and are willing to risk/invest, your objectives, your tolerance for risk, your time horizon, the time that you are willing to or wish to devote to monitoring your investments, and others. The best investment for one person may be the worst for someone else. For example, you mentioned buying Sun at 7 and selling it at 5 1/2. That trade suggests a willingness to be somewhat aggresive. But on the other hand, you are have purchased a Vanguard Index Fund, a much more conservative type of investment.
So, what are you? A trader with a short-term horizon (SUNW), or a longer-term investor looking for appreciation at least equal to the overall market (an index fund)?
Though I am a twenty five year veteran of Wall St and made my living by trading for many years, the only advice that I will give you is to (1) take maximum advantage of tax-deferred programs, and (2) clearly define what you want from your activity.
For many people, and especially younger people working for a salary and without a large investable pool, the best investment vehicle by far is either a 401(k) or an IRA. The tax advantages over the longer run are simply too great to be ignored. Use a self-directed IRA or 401(k) if you must, but by all means take advantage of the ability of these vehicles to accumulate tax free. Over the long run, it is a huge advantage.
Other than that, if you still have the urge and have investable funds, you must then decide what you want out of it (the fun of trading, the satisfaction of long-term trading, or whatever). Once you have decided, its time to educate yourself on the ins and outs of your chosen approach. Read voraciously, discount much of what you read. Everybody is an expert. Everybody wants to help you - as long as there is something in it for them.
Jeez, sorry, didn't mean to carry on so long! Hope this helps and best of luck.