Suggestions for the best value for the money on desktops right now?

I work as an office/network manager of a small (13 desktops and a server running Windows Server 2008 on a network) church office and have FINALLY been given approval for purchase of 6 desktop pcs and a couple of laptops. I want the desktops to have 6-8 GB RAM, 300-500 GB HDDs, Windows 7 professional 64-bit OS and preferably no added junk or at least the option to have the added junk removed before delivery. I don't want CHEAP computers, but I do want machines that are good values for the money spent. We have been using Dell Optiplex GX 260s, a couple of Gateway dinosaurs, and a couple of AVA-direct-built pcs over the past 3-12 years and have had few problems with them. As each has crashed, I have done two image restores and/or backup restores, given each a new hd, put in updated network cards and/or video cards, maxed out their memories, and then gave each a couple more image and/or backup restores... in other words, I think I've squeezed enough blood out of these turnips. Working for a small church environment, though, I want to make an informed decision on the purchases and be a good steward of the church's limited resources. I have had great experiences with both Dell and AVA-direct. Do you have any suggestions based on your personal experiences? Thanks in advance for your consideration!
Debbi