You need to be more specific as to what type of attachment you're having problems with.
Depending on the attachment, you may need to buy or somehow get the program that opens that type of file. Example: You have a brand new PC/laptop, with nothing on it, except the Operating System. Let's say you had a free sampler of MS Office or what have you, but the trial period expired on it. That's the same as having nothing at all.
Next, you go to your email and find an MS Word attachment. You can save the file, but you still need MSOffice to open the document.
There are other more common attachments, that you can open with free "readers" or "viewers" for them. An example is a .PDF file, that Acrobat Reader can open. If you don't have this software installed on your PC, the web site will usually prompt you to go to the manufacturer's web site, where you can download it for free.
Most of these utilites get installed and become part of your browser or email program, and are called "plugins".
Depending on your Operating System, you need to go to either microsoft.com, apple.com, etc, and do a search on "plugins" for your browser.
There's a free, open source program called Open Office, from www.sun.com
, that is compatible with MSOffice. If you download and install it, then you will be able to open all the different file formats, like presentations, text documents, databases, etc. However, you have to be careful when you create new files. You have to save them in the MSOffice file format, for others to be able to access them. This is because the default file format is its own, rather than MSOffice's.
If you don't, you'll create for your recipients the same dilemma you're having right now!