It is absolutely better to get 1 piece of ADSL+Wireless Router for several reasons......:
As for your purchase:
My findings:
First: i got a Netgear ADSL+Wireless router, forgot its model name, which didn't work in the begining with sodetel but eventually it did after many attempts but i wasn't sure whether the problem was the router itself, ISP, or an interrelated issue between both (found few reviews of ,might be the same or other Netgear models..i can't recall :/, having ADSL connectivity problem) but i eventually changed it due to WiFi issues to the following router:
D-Link ADSL+Wireless Router: DSL-2740U Wireless N ADSL2/2+ Router; for ADSL connection speed, it supports 24Mbps downstream and 1 Mbps upstream. (LAN Wireless speed: up to 54Mbps (802.11g), 300Mbps (802.11n).
check its datasheet for more info...
It is fantastic, simple, cheap, and it worked smoothly with Sodetel.
http://www.dlink-me.com/index.php?navigation=products&owner=28&product=29&product_details=289
Still,
Your suggested one: Linksys X3000 Advanced Wireless-N ADSL2+ Modem Router @
http://home.cisco.com/en-apac/products/gateways/x3000, has few more advanced advantages as indicated such as faster LAN ethernet ports and StorageLink USB; "Built-in StorageLink port and UPnP media server" etc...
make sure you compare both for features/advantages and check their reviews and ratings....
I won't say if your Linksys will work or not with Sodetel, but there's no reason why it shouldn't.
so, the final decision is yours. Good Luck!