Wow, people really defend their lens choices. Here's what's in my bag now (all Canon):
10-22
50 1.4
24-70L
Before I bought my L lens, I used the 50 1.4 the most. I was in the same boat as you before (I had an Xsi) but felt the kit lens was too slow and didn't give me enough bokeh. I bought a used 18-200mm (kit lens for the 50D-7D) but I had the same issues. The 50 1.4 solved that for me but it didn't have any zoom which kinda sucked.
I ended up selling my kit lens and the 18-200mm, saved for a while and got a 24-70L. The jump in image quality from the L lenses is phenomenal. The 24-70L and the 70-200L are both amazing lenses.
If you don't mind buying used, check Craigslist and here:
http://photography-on-the.net/forum/index.php
^I bought my Xsi and lenses from there. Same forum rules when buying!
The only advice I'll give you is pay the difference between the 1.4 and the 1.8, I think it's worth it. The 1.8 is made of cheaper materials and a lot of people have had them fall apart. The 1.4 is a great lens, if you buy it you'll probably end up keeping it. Low light conditions never go away
