I generally would agree here, if it ain't broke don't fix it. the 2.4.26 kernel is reasonably current, and the 2.6 series kernel is putting me (and many others as well, it seems) through my paces.
If you were into upgrading your kernel a bit, you wouldn't be asking this, but the 2.6 series kernel seems to copile quite a bit faster. And the xmenu config is nicer.
Despite the inclination to say "don't worry about it", and seeing as you have experienced 2.6 already (due to the wireless card), i doubt there is any real benefit in upgrading. I am seeing a more responsive system overall, but my laptop is still running 2.4.26 as well.
Returning to the sentiment, if it ain't broke don't fix it. 2.6.9 seems reasonably stable. (KDE, X and nvidia drivers are giving me grief, but only when i want all their features at once). 2.4 works great so hey, if you lack features under 2.4 stick with it