Adam Internet and iiNet recorded traffic spikes overnight which they have attributed to the interest in Windows 7.
"We have noticed a significant increase in traffic of up to 50 percent more than usual, wanting to take a look [at Windows 7]," said Adam's managing director Scott Hicks.
iiNet chief technology officer Greg Bader also produced graphs for Perth that appeared to show a sharp rise in traffic.
"We did see an increase in our Akamai traffic from about midday yesterday," Bader said.
"We presume that [Windows 7] was [the cause]."
In a post to Whirlpool, Internode managing director Simon Hackett attributed congestion being experienced by Tasmanian customers to the availability of Windows 7.
He did not rule out increasing Telstra Wholesale capacity to cope with the increased demand for bandwidth.
"In the last day or two something tipped the link into hitting evening congestion," Hackett said in the post today.
"Our network engineers believe it's most likely to be the release of the Windows 7 RC.
"We're going to crank up yet another upgrade to our Telstra capacity if the congestion doesn't stop occurring again the next day or so. This upgrade should be pretty fast to deploy if we need to do it."
Internode told iTnews that data levels in general were up "about 11 to 12 per cent above typical demand for Tuesday night and that elevated level of demand has continued into today."
"Although it is not possible to specifically track where that extra data originated, Internode notes that much of it came from Akamai server farms, which we believe are delivering the Windows 7 RC software downloads," an Internode spokesperson said.
Telstra's BigPond is the only ISP so far to not identify a surge in Akamai traffic due to Windows 7, according to a brief statement provided to iTnews.
Microsoft downloads - such as the Windows 7 RC - are mirrored using the global Akamai network.
When users click on the link to download RC from the Microsoft.com, it redirects them automatically to download from the closest Akamai server.
Microsoft has warned users to go easy on its servers, reminding them the download is available until the end of July.
The Akamai network has previously been used by the likes of NASA to stream shuttle missions live on the internet.
The company also claims billions of songs from "the top online music platforms" have been delivered across the network.