At my place of work, had 2U 2-way Opteron servers been available in the IBM XSeries (our company server standard), it would have been a no-brainer to go with Opteron. As it was, we went with XSeries 345 2-Way Xeons for all of our server upgrades this year. The 1U XSeries 325 would have forced us to go with an expansion chassis to get the additional drive space needed, thus making it cost prohibitive (or at least less cost competitive).
Dell timed the upgrade cycle well with a lot of large deals.