Never crimp your own cables except in extreme circumstances, they are too easy to get wrong. Even if you're good at it, it's easy to accidentally mix stranded wire and solid connectors, or the other way around, etc.
I usually just keep around a bunch of selection of 1',3',5' and 7' cables for desktop and rack stuff, and a couple odd long ones for when something comes up.
And Widebody is right, you're not going to gain anything if you're <1Gbps by replacing the old cables.
You can make it much prettier though, and that is quite important.
