I just checked Dell's Web site and if your computer is a Dell Inspiron 5000, the minimum RAM it can have is 32 MEGS, not 512 K. VectorLinux Light certainly cannot run in under a meg of RAM and I don't think any other Linux can, either.
If you have just 32 megs, Light will run but badly, according to reports on this forum. With 32 megs you should probably forget about a GUI and just run console applications. With 64 megs you'll have more options including a GUI (I think JWM is less demanding than IceWM), but even with 64 things will be slow.
Firefox and SeaMonkey are not going to do well on 64 megs. Dillo would be your best bet, but it is limited in what it can do. There are some lighter GUI browsers but I'm not familiar with them. Opera is thought to be lighter than Firefox, but it still requires a fair amount of RAM. Forget about OpenOffice. It would be unusable on 64 megs. If you really have 32 megs, forget about all of these and be resigned to text programs. Lynx and Links are text-based browsers, there are several e-mail programs, and there are a number of console text editors.
Even Linux can't work miracles.