Dominic:
Try checking out markettide.com and check out Trading System Testing Software. The price is for less than $50 but you need to input your data by hand. Also, for a price, the author will taylor the program to your needs.
If you have IB as your broker, check out Maxtrader.com. This software will keep tract of your trades you made through TWS and among other things, create an equity curve and the data is downloaded into the program. Also, it prepares the stats need for your year end taxes. The light version is about $199.
Finally, check out armencomp.com for their accounting software which I believe also calculates and equity curve from the data furnished by your broker. I supports downloads from a number of on line brokers.
Hope that helps