Make sure to get a good sales rep. If you don't, ask for another. Advocate and you'll find one that is solid. I just happened to luck out.
For hardware, regardless of their reported inventory levels, shop and commit early. The good units will go surprisingly quickly.
We primarily purchase Lenovos, and have been very pleased with PCM's handling of the product as well as Lenovo's support.
The extended warranties can seem pricey, but I have had to use them more than a few times and they have more than paid for themselves in the long run. Review collected by and hosted on G2.com.