RC servos are easily drivable from an MPU port. They just take a low current pulse width to determine the servo position. There are a few overloaded definitions for "servo motor" so depends on what you are talking about. But RC servos work fine with just a common MPU pin driving them. Now, you might want to POWER them from a separate power supply (keep the grounds together) but the "logic drive" can easily come from the CPU.
I'm not a big fan of the Arduino. The standardized "shields" are a good thing, but the IDE software bothers me (but I still code in emacs for everything so what do I know?).
If you just want to do PC control here's a few things to consider:
http://www.awce.com/gp4.htm - Servos. Add a USB cable.
http://www.awce.com/gp3intro.htm - This board will control servos and lots of other things via USB cable. There is a USB "native" version in beta, but that just means the USB to RS232 is built in -- still looks like a serial port to the PC. The interesting thing about this board is you can program it "point and click" on the PC and then download the "program" to the board so it doesn't need a PC anymore. But all the debugging is done with the PC. You can use it from the PC with lots of PC languages too. Video:
(a few others on there, including a robot).
For "regular" microcontroller projects, I've become a big fan of the AVR for small cheap stuff (yes, the brains behind the Arduino) and ARM for the bigger stuff. Futurlec (sells in Australia, ships from Indonesia, slow as Christmas in the US) has a very inexpensive ARM "Stamp" that I like very much. Free C compilers and the thing is bigger than most of the PCs I've owned in the last century:
http://www.futurlec.com/ET-ARM_Stamp.shtml but next one I buy will be this one:
http://www.futurlec.com/ET-STM32_Stamp.shtml. Think about it: 1/2 megabyte of program storage, 90 MIPS, 48 I/O, 16 A/D, 2 D/A, and 64K of RAM. I remember when that would have been a fairly big PC ;-)
Hard to beat for US$25. The bootloaders mean you just need a serial port -- no programmer.
Anyway, just a mix of things to think about.