When you apply for your 501 status you may or may not be approved by the IRS as a 501c3 the IRS may define you as a different type of charity that does not provide for tax deductibility for your donor's donation.
I would approach your donors during this time based on your mission and the needs you are trying to fulfill over the ability of your donor to get a tax deduction. You may also look to your board and volunteers to get some "skin in the game" because of your cause.
As far as my understanding with Tech Soup you will need the official IRS letter to prove your status.
In regards of the products you were looking for from Tech Soup, we may be able to suggest some no cost or low cost alternatives to get you started, some examples are
Microsoft Office -- Open Office
File Server software -- Free Nas
Fire wall -- m0n0wall
Dave