However, some frustrations with ATNotes bothered me, so I've started looking for alternatives. Usually I do this be searching on google for "ATNotes alternativeto" (without double quotes), which displays the alternetiveto.net site.
Luckily, I found a wonderful alternative which is named Stickies. I've installed it and found it great, simple, lightweight and doesn't interfere with your system or registry.
If you still need more alternatives you can check the list on http://alternativeto.net/software/atnotes/.
More interestingly, I found that the company that made this utility also made some interesting utilities which I name a few here:
1. Stickies (The already mentioned sticky note utility).
2. ZBar (multiple task bars for multiple screens)
3. Bart (A wonderful simple backup utility).
4. Caffeine ( A utility that simulates a key press every one minute to avoid your PC from stand by or screen saving).