This procedure varies a little bit depending on what wireless device you have, and by distro. Most importantly first, we need to know exactly what wireless device you have in your machine. My roommate just recently installed Mint-9 on her Acer e-Machine also, and when it started up, it told her that "there are 3rd party drivers available for this machine" and she had to choose the Broadcom STA driver for her wireless. Upon choosing to install that driver (which was included on the Mint disc) the wireless started working on its own - I was impressed, it was very easy.
So anyhow, about your wireless device; please show us the output from the following command:
That will produce a long list of paragraphs, one paragraph for each PCI device in your machine. Your wireless should look slightly like below:
05:06.0 Ethernet controller : ADMtek NC100 Network Everywhere Fast Ethernet 10/100 [1317:0985] (rev 11)
Subsystem: Motorola Device [1057:7310]
Flags: bus master, medium devsel, latency 64, IRQ 19
I/O ports at e800 [size=256]
Memory at febffc00 (32-bit, non-prefetchable) [size=1K]
Expansion ROM at febc0000 [disabled] [size=128K]
Capabilities: [c0] Power Management version 2
Kernel driver in use: tulip
Kernel modules: tulip
..except it will say something about 802.11 wireless or whatever. The example above is from my wired ethernet card.
Once we know what the device is, someone will be able to advise how to go about getting the driver for it, and installing it. You have one very good benefit right now - working wired ethernet, in case you have to download something. With any luck, your device will not be some really weird, rare crazy wireless.