If your former linksys router was NOT N but rather b/g, then the problem is likely that your new router is running N and must be reconfigured to run b/g instead of n on its wireless. The acer aspire one netbook's integrated WiFi is 802.11b/g and the only way to do 802.11n is by using a plug-in USB 802.11n wireless adapter. To manually configure the router's wireless for 802.11b/g or n...
1. Connect the netbook using an ethernet utp cat5 patch cable between one of the four RJ-45 LAN ports on the router to the 10/100 ethernet RJ-45 port on the netbook's left side.
2. Start a browser like Internet Explorer and enter IP address 192.168.1.1 (default for Linksys)
3. On the login window, enter admin for username and admin for default password, then click OK
(The password may be changed if the router's setup software on its CD has been run.)
4. On the Linksys Setup page, click the Wireless tab
5. On the Linksys Wireless page, for Network Mode, click v for drop menu and click BG-Mixed
The preceding is from Chapter 3: Advanced Configuration which starts at page 16 of the 59-page Linksys E2000 user guide/manual. If you are missing this manual, it can be obtained by clicking...
http://homedownloads.cisco.com/downloads/userguide/E2000_UG_USA_V10_NC-WEB.pdf

A final note: The easiest way to setup the router is to run its setup software on the CD that comes with it. If you want to do this with the netbook (which doesn't have an internal CD drive), an external CD drive would have to be plugged into one of its USB ports.