I used to use a normal wired keyboard with a long USB extender from Monoprice. It wasn't always attached as I didn't need it often. I found this Logitech Bluetooth keyboard on Slickdeals for a good price:
http://www.logitech.com/en-us/keyboards/keyboards/cordless-mediaboard-pro-for-ps3
I also bought an ASUS Bluetooth USB adapter from Newegg for $0 after rebate, which just made it all the much sweeter.
When I built my i3-540-based HTPC, I opted to nix the optical drive as well. You can simply copy the files from the Windows 7 install DVD to a thumb drive and boot from it. If you don't have a Windows 7 + SP1 disc, you can find download links (straight from Microsoft's CDN) for ISOs. I considered using it for Blu-Ray play back, but the drives weren't terribly cheap at the time. Also, if you're using a nice looking, small case, it might require a slim drive. That will just add to the cost. This doesn't include the fact that these drives usually
do not include BR playback software, and if they do, it's crummy OEM junk. The OEM will playback the video, but the audio is typically limited to some reduced capacity (such as 2-channel). The good BR playback software will run you between $80-100. This also doesn't include the fact that not all media centers integrate with it well. WMC does, but it also doesn't natively handle all popular formats without a little tinkering. Personally, I could never get MKVs to work in it.
Yeah, I just use my PS3 for Blu-Rays.
In regard to using the integrated graphics, I'm not a huge fan of them. I just don't like the Intel configuration tool. I still cannot get it to properly fix the overscan on my TV, but it's close enough that I'm only cutting off maybe 3-5%. XBMC has settings that allowed me to correct it the rest of the way (in XBMC only).
EDIT:
I also threw a 40GB SSD in it. I mostly just care about the snappy response and quick rebooting. I will usually randomly perform Windows Updates on it.