Since you don't appear to be a hardcore gamer or extreme overclocker you don't need the latest and greatest processor or expensive motherboard and ram. On the other hand you did mention occasional gaming so a dual core processor would be a good choice. It also sounds like you're on a budget. Check prices at newegg.com and pricegrabber.com. If you have the time check periodically over a one month period. The vendors often have specials. Sometimes the bargain basement prices are only good for a couple of days. I've even seen one day only bargains. You may luck out.
You're best bet if it's within your budget would be the E5200.
This forum has a very large group of hardcore gamers who are into serious overclocking. A lot of the articles and reviews are for gamers. What I am about to say is totally different. If it weren't for the occasional gaming you mentioned, then an old Intel Pentium III 600Mhz cpu would meet your needs which are minimal.