Software to help computer users make investment decisions and manage their finances has been around for a while, but it's easy to get confused by the plethora of packages available.

Since this software varies so much in price, you can end up paying too much. Think of it in terms of buying a car. How powerful a model do you need, how experienced a driver are you, what optional extras are there, how much will it cost to run, and will it fit in your garage?

The "will it fit your garage" aspect is easy. You need to make sure that you have enough space in your computer hard-drive and enough computer memory to store data and run the program to best advantage.

If you're a newcomer to investing, or to charting, it's best to choose an entry-level package that has various functions and offers easy access to data. You can always upgrade and some of the big software houses have a trade-in policy that makes trading up relatively easy, by letting you pay just the difference between one package and the next one up the scale.

What options do you want factory fitted? Increasingly investment software combines the two main themes of investing: charting (or technical analysis) the graphing and interpretation of share price movements on the one hand, and accounting fundamentals and company news on the other. Many packages also offer the ability to monitor your holdings, and can generate capital gains tax calculations, portfolio analyses and the like.

Like cars, some software packages can be expensive to run. Importing data, rather like filling up with petrol, can be costly. To start with, go for a simple package that offers an easy means of importing end-of-day data. This could be something as simple as entering prices manually, paying for a weekly disk with price updates, or getting the information by e-mail, from the Web, or by dialling into a database.

Most end-of-day price data are free. Packages that have fundamental information often make a small monthly charge. Real-time data are more expensive and only for the experts. Again, the best plan is to start at the cheaper end of the scale and work up.

Can you take a test drive? To get a real feel for how a package works on a day-to-day basis, you need a demo. Many software companies offer these, and they are a must before committing yourself. What does the whole thing cost? Simple packages are available for well under £100 sterling (€160). Data can be free.

Alternatively, a typical "fundamentals and data" offering may have a modest one-time cost of around £50 plus data costing £10 a month. More elaborate specialist packages, or those specifically designed for in-depth chart analysis using real time data can run well into four figures.

The Web has changed both the cost of investment software and the accessibility of charting and portfolio management tools. For a start, some investment software is downloadable from sites such as Download.com (www.download.com).

Charting and financial information is also available on the Web at the usual financial portal sites.

Finally, if you need to monitor your portfolio, portals have monitoring services that will do that, some more sophisticated than others, but most offering the ability to track your individual holdings, profit and loss, uninvested cash and so on.