I was just fooling around with the practice forex for a couple of hours today and made around $5k profit.

Answer
The simulations frequently do not match real world conditions.

Quoting from a federal government website:
"Real-time is not real: when marketing trading systems, some promoters claim that their systems have performed successfully in "Real-time Trading." This means only that the system has been tested using a live data-feed, rather than being tested using historical market data.
Remember though that in real-time trading, no trades have actually been placed in the market. Performance results based on real-time trading are merely another form of hypothetical results, with the same limitations. "

Where can I find historical financial data that can be imported into excel?

I know that yahoo finance allows you to download most indices, but im talking about a broader range of things (forex, pre-market data, commodities, bonds, treasuries..etc). I'm not concerned with it being free, I'd actually prefer paying assuming the data would be a little more accurate. any websites that offer premium data?? Thanks.

Answer
Download NinjaTrader for a free trial. The forex and futures data feeds through Zen-Fire are free.

http://www.ampfutures.com/index.php

You can build your own historical database as you go, or purchase historical data. Here are the different paid data feeds for NinjaTrader
http://www.ninjatrader-support.com/HelpGuideV6/helpguide.html?HistoricalData

Here are some free download sites if you want to use Excel. But Excel is so primitive compared to a trading platform that handles all the different time frames for you (1 min charts, 30 min charts, hourly, daily, monthly, etc.) and includes all of the indicators and moving averages and candlesticks and bar spacing, and on and on.

Stock Market Indices and Forex Data
http://pitrading.com/free_market_data.htm

Forex historical data download
http://www.fxhistoricaldata.com/

More Forex data
http://ratedata.gaincapital.com/