97 vw golf oxygen sensor

Just wondering if anyone has any experience with changing an o2 sensor. My check engine light came on awhile ago for a sensor related problem but pretty much ignored it as it wasn't giving me much grief. Yesterday the car was being pretty sluggish, losing power and a few times felt like it was going to stall.
I'm pretty good when it comes to doing my own mechanical work but haven't touched it before, how long would it take to change?
probably doesn't matter but its a 2.0l 97 golf with 101k miles on her.

as long as they arent seized up around the threads, not too bad typically. all depends on how easy it is to get to.

What was the code. Did you have it scanned and are you sure its the O2 sensor. Was it a lean code or rich code. Or a heater code.?????

oh noes

i get code p0134 - no activity detected on o2 sensor
and p0135 - o2 sensor heater circuit malfunction.

as easy as changing a sparkplug