Ethel
dsl and adsl are essentially the same thing (DSL - Digital Subscriber Line is just the generic) .... the A denotes the subclass Asymmetric (faster one way that the other - generally downstream is faster).
Lil' Miss
I assume that what's being asked is can the modem controlled internet feed be extended (using the orange box as a Wireless access point - WAP) - so that others can share it.
the answer is yes - you should be able to ..... wheather it's actually a practical solution is another matter
If the "modem" has an ethernet port on the back ... easy ... all you need is a crossover cat5 cable between the two devices.
if not
first you'd need to setup internet connection sharing (
http://www.annoyances.org/exec/show/ics)
and connect the PC to the old router (either wireless - which is difficult) or using a cat5 crossover) - so the old router is being used as a wireless hub (wap)
in the long run ....
the downside is you'll need to have the PC switched on whenever someone else is surfing