If you own XP i'm told that it has a built in editor.
If not Then starting at the top end there is Adobe Premiere. Quite expensive but good.
Second Ulead Media studio. Still a bit expensive, but good. Have used this in the VE version which came with firewire card. I liked it. Similar to Premiere.
Then at my price comes Ulead Video Studio which is reasonably priced and easy to use. I have used this and it is quite good.
There are free ones about on the net but some one else will ned to point you in that direction.
If you are going to edit video I assume you will need or have a capture card. This usually comes with some form of edit programme. Maybe you have one already.
Regards Brian j