I doubt you'll need to replace your servos.
I can't give you any details as I'm not familier with your plane and I don't have time right now
to do all the research but here is an idea of the equippment you're looking at getting.
you can get good deals at hobbycity.com

1) you'll need a brushless motor (big/powerful enough for the plane) and
2) matching speed controller (matching, meaning one rated at the amperage your motor draws depending on how you prop it)
3) Electric props I use APC brand I'm not sure what size as I have no Idea the size of the plane you have
4) I'd suggest LiPo batteries, again, rated to match/exceed what your motor draws (read read read)
5) you'd need a charger for those batteries, and a ballancer or a charging ballancer
6) lots of reading to learn how to handle those batteries (they can get very dangerous if you're careless)
if you treat your batteries right you can get upwards of 70 cycles out of them and although that doesnt seem like a lot it actually is!
7) Soldering iron
8) Possibly deans connectors depending on the batteries/ESC/motor some dont always come with these things attached
9) a watt meter (I dont have one, I use the reviews to get a good idea of what I buy and what to expect. but ill get one soon)

here are some examples

.60 size motor
http://www3.towerhobbies.com/cgi-bin...?&I=LXLWV8&P=7
.46 size motor
http://www3.towerhobbies.com/cgi-bin...?&I=LXLWV6&P=7

these require between 60-100A speed controllers (ESC) those are towerhobbies links for motors but you can get similar motors
at hobbycity for better prices its up to you.

check these out

http://www.hobbycity.com/hobbycity/s...idproduct=4907
http://www.hobbycity.com/hobbycity/s...idproduct=2098
be sure to read the reviews

Ballancer
http://www3.towerhobbies.com/cgi-bin...&I=LXMGS7&P=ML

I use this charger
http://www3.towerhobbies.com/cgi-bin...?&I=LXKSY1&P=7

All in all going electric is expensive!
but I do like it! and am not interested in fuel

ok so i've got to run! but I hope this is a good enough ball park idea of what you're looking at.

if you've got a smaller plane some where around 2lbs or less the motors i listed wont be for it!
what i've listed are for size .40 to .60 glow to electric conversions around 4-7lb or a little higher

Good luck I'm sure others on here will be a lot more helpful than I can be rigth now