AMD 3700+ vs Opteron 1218

I have a small webhosting server running on a AMD 3700+ currently, and as it is, its really reaaaallllyyy idle atm, since there's only a few test domains on the server at the moment, now.. hopefully things will change over the next couple of months and I should get the opporturnity to host a few more websites, mostly php / mysql websites, but in due time, more demanding stuff like RoR and CGI will come into play and demand a wee bit more from the server.. So, for a webhosting server, how much more power would I get from the Opteron 1218 with 4Gb DDR2-667 ram vs my current. AMD 3700+ with 2Gb DDR2-400 ram.. both running Debian 4.0 32bit with DirectAdmin.. and ONLY for hosting. nothing fancy here..

and.. infact, would it at all be profitable upgrading to a Opteron 1218, since I could get 2.6 x AMD 3700+ servers instead of 1 Opteron 1218..