Can an older Round Airport Extreme and Airport Express be used on my home WIFI network?

Question

I recently upgraded my Macbook Pro to a newer one because I was having problems with the older one getting on my home WIFI network.  It had been dropped, but had continued working without any hiccups for five or six months.  Suddenly it won't go online.  It said there was no WIFI hardwae installed.  I suspect that the WIFI antenna connection between the main bdy and the display failed.  Repair options at the Apple Store were iffy, so I just baought the new one.  My Time Machine backup smoothly cloned my old machine onto the new one. 
In the "when it rains it pours" category, my Airport Extreme also failed at the same time I began having problems with the old laptop.  Suspecting the hardware was the problem after checking with my ISP, I purchased a new Airport Express at Best Buy.  Using it, I got my WIFI network back up and running.  That's why I figured there was a problem with the older Airport Extreme.  The Airport Extreme was replaced by an Apple Genius at the store, when I purchased the new laptop.  Putting my Home WIFI network back together with the new AE, went fine, but it turned up another problem.  I use an older (pre-N speed) Airport Express to link a YAMAHA digital piano wirelessly to my WIFI.  It can go online directly and download music.  I can also push my iTunes wirelessly through the piano's amplifier and speakers for great sounding stereo.  The problem is my new AE won't recognize my older Airport Express.  I tryied downloading the Airport Utility v. 5.6 as suggested online, but It still won't find the Airport Express hooked up to the piano. 
Is there any way to update my earlier Airport Express and also an older Airport Extreme (round)?  The Airport Utility v.5.6 won't recognize them and initialize them.  Any ideas?  I repurposed the new Airport Express I bought to seerve my printer, allowing me to disconnect the USB cable from my iMac.  That's working fine, except my HP OfficeJet Pro 8500 now won't give me two sided printing anymore.  It always something!
Network consists of:
20" Mid 2007 iMac running Mac OS Lion 10.7.4
New 15" MacBook Pro running Mac OS Lion 10.7.4
HP Officejet Pro 8500 All-in-one Printer
New Airport Extreme attached to DSL Modem
New Airport Express wirelessly attaching my Printer to the network
Old Airport Express (A/B/G) connecting my Yamaha Digital piano (NOT WORKING)
Old Airport Extreme (round) (NOT WORKING)

Answer 1

Bob,
Thanks for your help.  At this point, I'm seriously considering replacing the older "g" AX with a new "n" model.  For whatever reason, each time I've tried to bring the ols AX bcak online in my network, it only managed to screw up my network.  Using the Airport Utility 5.6 for Lion, I was able to get a green light on the AX, but it still would not go online from my Yamaha digital piano control panel, like it always did before.
Using AUtil 6.0, everything else works, and I'm assuming that setup with a new "n" speed AX, my piano will be able to get back onlune, too.  When I originally set up the AX to link the piano to my WIFI network, I had very little trouble getting it setup.  YAMAHA didn't list the Apple AX in it's list of compatible wireless routers/adapters, but I saw no reason that it wouldn't work.  As I said it was a reasonably easy setup the first time, and it has worked for several years with no problems.
It's not the cost of buying the new AX that bugs me, it's the fact that I can't figure out why it won't work now when it did before.  It was working fine with my old AE based WIFI network, even after upgrading the my computers to the Lion OS.  I used to be reasonably savvy with Apple technology, having spent the last 15 years of my teaching career (1987-2001) as the tech liason for the schools where I worked, supporting first Apple II's, then Macs, and networked buildings.  After eleven years of retirement, I find it harder and harder to keep up as the technology just keeps evolving.  I'm trying, but it's not easy!  Any and all help is appreciated!