Ultralights – Also known as sub-notebooks or ultraportables, this style of laptop weighs up to – but no more than – four pounds, making them ideal for travelers. The upside of an ultralight is that it doesn’t burden those who have to spend a lot of time carrying them with aching muscles, as its larger cousins often do. The downside, however, is that – in order to cut down on size and weight – this type of laptop is so small that there’s no room for a network card or internal CD drive. In order to reap benefits of these types of “attachments,” you’d have to bring an external CD drive and port replicator. Another negative in scenario is that ultralights tend to be on expensive end of laptop spectrum.

Notebooks – This is basically just a regular laptop, but is slightly less heavy, weighing in at four to six pounds. While it’s heavier than smaller ultralight, it also offers more options with less fuss. Offering flexibility of a combo bay, notebooks are designed with a large opening on side which allows user to plug a CD drive, floppy disk or extra battery – allowing you to access features that you need without burden of making room for those that aren’t needed.

Shared Library Files

Many software firms use DLL (Dynamic Linked Libraries) in developing programs. They are kind of like a tool box from which programmer chooses one needed. Even though program being created may need only a couple of "tools" from this DLL, using them saves programming time, which is expensive. This is a safe and efficient procedure, for code in library is well tested and will run reliably.

Other software developers use same library. Some DLLs are used in many programs. For you, this means less disk space required on your system, for only one copy of library is needed.

You also benefit in that you pay less for software and it runs reliably. It's hard to see anything negative in such a procedure. Or in software using any other shared procedures. For example, you might have several programs that use a common routine that is part of connecting your system to Web over a phone line.

All About Versions

Most companies developing software will use latest version of a DLL. It contains changes and enhancements over earlier ones. Thus differences exist between them.

This is true of different versions of other software. The latest version of IE (Internet Explorer), for example, contains changes and enhancements over previous one. Migrating from current version to latest, can mean installing what amounts to almost a new program.

The Catch In Upgrading Or Installing Software

When you install an upgrade or a new piece of software, any DLLs used will also be installed. Windows makes rules in this. An older version of a DLL is not allowed to overwrite a later one. But a newer one IS allowed to overwrite an older one. Here's how things can go wrong.

Suppose you have a program call SPLAT, another called SPRANG, and a third call SPUNK. Suppose they all use a DLL called STUFF. If you upgrade SPUNK, and upgrade includes a new version of STUFF, then quite suddenly SPLAT and SPRANG may not run properly. That is, they are now forced to use a version of STUFF programmer had not planed for.