I bought a 7.5 FX last year - since then it's been totally customized - but the saddle was the first thing to go. I replaced it with a Terry Fly, but that's a $140 - $150 saddle. So try a few and see what feels right - IF the current saddle causes you pain.

For a bicycle-computer, I went for a Cateye Strada Wireless - around $50 - and it's never given me any trouble. Installation was simple. The batteries, that last a season, cheap if you hunt via Google. It just plain works.