for what it's worth, if you wanted to upgrade now, maybe go even lower. go with the 2x1gb ddr2 kits that are 20ar nowadays. pretty negligible, and you'd probably be able to even make money back by selling your old ddr1. then, for the cpu, either grab a e2180 or some other cheap e2xxx, or if you must, the e7200 is only $120. damned good deal. after some overclocking, it'd be damned impressive still. you won't be disappointed one bit, especially coming from an opteron 165 @ 3ghz. that'd let you wait it out.

For what it's worth, nehalem won't shatter the penryns, although certain things will obviously be vastly improved. In the long run, you'd have something that's still more than fast enough for today and tomorrow, and by tomorrow, nehalem and associated ddr3 prices will have plummeted.

All depends if you want to play the waiting game or buy now / soon. If you wanted to wait, you'd think it'd only be 6 months, but then it'd be a year, and by then, if you'd been patient enough, you'd be thinking "damn it, just another 6 months".