I was in the market for an oscilloscope, but I didn't want to spend much. I found out about Rigol and their line of $300-400 scopes, and was getting ready to buy one. Then I found a post on how to make your DS1052E, which costs about $400 into a DS1102E, which costs about $700 with a simple firmware modification! I bought the scope right after, and I received it in the mail today. It's pretty nice by default, but doubling the bandwidth is always a plus.
The DS1052E has a 50Mhz maximum frequency, but it has exactly the same hardware (as far as the reverse-engineering folks can tell) as the DS1102E, which has a 100Mhz maximum. This guide will show you how to make the switch very easily using Linux. You can do it in Windows too, but it's a bit more involved, and Linux makes it really really easy.
I've attached the Rigol user guide for both units, in case you don't have one.
WARNING: It's entirely likely that this completely voids your warranty. Make sure you know what you're doing - you can brick your scope if you screw anything up.
Step 1: Spec Comparison
Here are the specs of the 2 scope models. Our test to see if we've succeeded is by looking at the Time Base Range minimum setting - the DS1052E has a 5ns/div setting, where the DS1102E has a 2ns/div setting - a much more accurate view for sure!