You can get a wireless network adapter for the Xbox 360 for $76 incl free shipping on Amazon.com.

i always use wireless and i NEVER have a problem.

tho i pay for the top bandwidth that they provide . . .

You can get a wireless bridge. It is basically a wireless router that connects to another router through wifi. They cost about the same price as the official adapter. If you want mess around you can find a dd-wrt compatible router and hack it yourself but it is not for noobies.

Ok, I really don't know what's going on here, but I've been a 360 owner since launch and have used this product for years with no problems whatsoever.  I have a pretty fast internet connection (currently near 7mbps) and haven't had any lag issues.  I've played a number of online games fast and slow paced many MANY times. 

While it may be technically true that a wired connection is the best, the downing of wireless connections here as something unplayable (or even close) is untrue.  I'm proof positive of that.  Hope it works out for you as well.

If possible I would try for a powerline/homeplug kit.

TRENDnet has one too:

http://www.trendnet.com/products/proddetail.asp?prod=185_TEW-647GA&cat=66

It works much better than the integrated one in the Wii, especially if you have a Wireless N router or access point... The only problem is that you have to use the USB to ethernet and then the ethernet to wireless N. I suppose that in the case of the XBox360, you can plug it directly to the ethernet port.

Looks good, especially as the N band has less interference from cordless phones, microwaves, other networks etc so it should work better than anything built into a gaming console by far if you have an N spec wireless network.

Thanks for the help guys. I have to buy a small tv for downstairs because guess what...I just went LIVE. Played Gears 2 horde mode for a minute and turned it off. Borrowed my mom's tv btw

Gamertag is Xigmund and my PSN is Xigmund. Add me up. Good lookin out again.