Fortunately it's mostly good news from here on out. Despite using a 92mm fan at the back rather than the quieter 120mm ones found on many cases, the dc7900 runs very quietly; in fact it's practically inaudible when its drives aren't spinning up. Of course this is partially due to the only other active cooling in the PC being the PSU and custom CPU cooler, since the motherboard and graphics are passively cooled.
This arrangement keeps the PC nicely cool and the CPU cooler is very impressive for a business machine. It's a massive metal construction with fins and heatpipes, sporting a plastic shroud with a fan at a 90 degree angle that draws air in from the case's front grill.
As far as the rest of the internals go, obviously it's a bit barren compared to the usual monsters we get through, which are often crammed full of the latest technology. Two RAM slots are taken up with twin 1GB sticks of DDR2 leaving two free and two of the motherboard's four SATA ports are used by the DVD-writer and hard drive. Apart from this all the slots are free, including two full-size and one mini PCI-Express 2.0 ones, plus three standard PCI slots that are likely to come in handy on any business PC.
Further in keeping with the 'convertible' (i.e. upgradeable and multiple orientation) theme, cable routing is a bit messy thanks in part to spare power connectors for extra drives being left free and ready to plug in. Installation of drives and cards is also largely tool-free. As a last bonus, the case is incredibly easy to open, with pulling a simple lever all that's required to remove the right side panel.
It's worth noting an integrated mono speaker, which produces barely bearable audio. While the utility of a speaker in an office machine is debatable, it does save space not needing external ones for the occasional YouTube video during lunch.
Interestingly, on the software side of things the dc7900 comes with a Windows Vista Business license, but also with a downgrade to Windows XP Professional custom installed. Much as Microsoft might push its latest OS, especially in a business environment XP simply makes more sense. It has better stability, a higher rate of compatibility with older programs and external devices, not to mention being more integrated into most corporate support networks. HP also provides a trial version of the most extensive and up-to-date office suite available; Microsoft Office 2007. The only niggle here is that this version might cause compatibility issues with older office formats, but there are compatibility packs available from Microsoft for everything down to Office 2000.