As a consulting helping customers implement Exchange Server I also have to help customers with their hardware solutions, both servers as well as storage. Quite a lot of customers are using HP hardware. HP has a very usefull utility called the "HP Product Bulletin" that can help you select the proper hardware, compare various hardware selections and even get a "quick quote" from the Internet. This will give you a rough indication about pricing.
The HP product bulletin includes all HP hardware, ranging from laptops and desktops to servers and large (EVA) storage solutions.
It also includes information regarding products that are retired for a long time. For example, you can still find information regarding a "Compaq Prosignia 720 Pentium II", a model that was retired in January 2000!
The application is stored on your harddisk, and everytime you start it it checks the HP website for updates and if needed downloads the updates.
You can find the HP Product bulletin on the HP website: http://h18000.www1.hp.com/products/quickspecs/CD_Files.html