Just a quick answer to the original question. If you replace the stock filter with a filter like the Baader DSLR BCF Filter (this is for 400D, 40D, 450D, 50D, 1000D/Rebel XS cams), you can still use the camera for regular daytime photography. You just have to set a custom white balance. Also with the new filter you retain autofocusing.
The following are filters for each series of cameras:
Baader DSLR ACF I Filter: Canon EOS300D
Baader DSLR ACF II Filter: Canon EOS350D/10D/20D/30D
Baader DSLR ACF III Filter: Canon 5D
Baader DSLR BCF Filter: Canon EOS 400XTi (400D, 40D, 450D, 50D, 1000D/Rebel XS
These filters can be purchased from alpineastro.com.
I just modded my 40D and daytime as well as autofocus still work.
FYI...this isn't a simple drop and swap filter replacement. It's not an easy swap to say the least. It took me over an hour to swap the filter in my 40D and I have experience working with fine electronics. I take no responsibility if you decide to swap the filter yourself. If you want to have this mod done for you, pm strgazr27 on this forum as he offered to mod mine or google "hap griffin".