I don't know about the price difference where you live, but here in Sweden, the 3000+ OEM costs only $50 more than the boxed 2800+, and the boxed 3000+ is about only $300-400, and the diffs between the OEM 2800+ and 3000+ is even less. So I'd recommend the 3000+, because you get a fine performance boost for a small extra fee.
However if you just hold out a few more weeks, Socket 939 processors will be out, and you might want to wait for that. Unfortunately, those processors might or might not have a significantly higher price. In any way, I'd recommend waiting just two or three more weeks to see what the new S939 CPU's will cost, before making your decision. If the price of the 939 processors will be similar to the 754's, then I'd recommend the 939's, but if the 754's will be cheaper, or more importantly, offer a better price/performance ratio, then I'd recommend a Socket 754 processor.
In any event, wait until the beginning of June to see what the prices of the 939's will be.
My system: AMD Athlon 64 3400+ / Corsair 2Gb DDR400 / MSI K8T Neo FIS2R / ASUS Radeon 9800XT / Antec TruePower 550W / Maxtor DiamondMax Plus9 120 Gb / Pioneer DVR-A07