If you plan on receiving traffic from Google, then you definitely need to be concerned with the sandbox. Our site has been listed on Google since January of 2005, has a PR5 and over 10,000 backlinks, and we are still buried in the sandbox. However, even though you will be in the sandbox, it takes at least a year of link building to gain search results for competitive terms anyway, so you could almost argue that the sandbox isn’t as big a deal. You will rank for non-competitive terms right away.