This has been discussed on several threads (usually titled with a question as to whether to fix or not) the arguments break down as follows... Interest rates are at all time low so now would be a good time to fix but the rate you get fixed is usually higher since the bank is taking on the risk of the interest rates rising. Fixed rates are a premium product and you will be limited so they should only be taken on if you need to know exactly what your repayments will be. If you are on a tracker, you are in the best current position and it is likely that the banks will be keeping a close eye on where the rates are likely to go and will have priced their products accordingly.
Basically you should really compare like with like, if you are inclined towards fixing your rates generally then now compares favourably, if you are not then it is only a consideration if you are worried about absorbing an increase. Personally I would not be inclined to fix unless I was close to the limit I could manage to pay. Fixing is expensive, if the rate you get over a ten year fixed deal is about 5% rates and rates didn't start to increase until the middle of next year (which is not an unreasonable surmise) you'd need to see rates increase considerably and/or quickly over 5% before you'd be the gainer.
(Using Karl Jeacle's mortgage calculator to run some scenarios)
For example €100k @5% over 20 years fixed for 10 years in the first ten years you would pay back €44,415 in interest alone.
In the unlikely case where you are lucky enough to be paying back 2.2% for those ten years you would pay back €18,492 in interest alone (of course chance would be a fine thing!).
If the rates were to rise 1% in 6 months, then another 1% 6 months later, then 2% 6 months after that and remains at that level (6.2%) for the remainder of the term then you would pay back €48,339 in interest. In short what I am saying is that you'd have to see a pretty steep increase before you are out of pocket by sticking with the tracker. I can't see the interest rate increasing that steeply simply because it would probably be viewed as being liable to derail any recovery.