I understand your thought process on the software is more efficient so it might work better on an older machine. And hey, prove me wrong. But I am just saying if you don't have to spend the money, perhaps put it towards a new machine? I dunno, just giving you my approach to such a problem.
I have problems finding pics in my iPhoto too sometime, and I started using the keywords feature. It's helpful. But do note that I have an iBook 1.33gHz w/1.5 gb RAM and iPhoto tends to chug on me. I had trouble with GB as well when applying filters. If you're just looking for a sound recording program (for quick demos) I can recommend SoundStudio.
I'm currently using a friends spare lisence of Traction 2, which I really like. But I'll have to give it back, so I'm thinking I might look into Garageband rather than Traction 3, because of the crappy drums you get for free.
I had a look at SoundStudio, but it seems to simple for me. Too Audacity-like.
Which version of iPhoto are you using? Going from iPhoto 3 to iPhoto 6 was a dream. It was extremely fast. No more beachball of death ever! I can scroll through the <4697 pictures without my computer chugging at all. I've just installed iPhoto, though. I'm thinking I might jump right on the new Garageband.
I tried the keywords-feature, but I'm not going to sit down and index every picture. I've indexed a couple hundred, before I got bored. The ultimate feature in iPhoto would be face-recognizion and automatic name-indexing.