Windows Virtual Memory
For Microsoft Windows, creation and management of virtual memory files (called "paging files") are handled more or less automatically. You can, however, adjust the initial and maximum size of the paging file for a given disk. Consult your system documentation for details and instructions on how to perform these operations

UNIX Virtual Memory
For UNIX, The size of the swapping area(s) determines how much virtual memory your process is allowed. To increase the amount of available virtual memory, you must increase the size of the swap device (sometimes called the swap partition). Increasing the size of a swap partition is a time-consuming task that should be planned carefully. It usually requires saving the contents of the disk, reformatting the disk with the new file partition sizes, and restoring the original contents.Some systems offer the alternative of swapping to a regular file. This is a considerably easier solution, although it may not be as efficient. Consult your system documentation for details and instructions on how to perform these operations.

Efficiency:

Unix offers more performance at 1000MB than Windows NT offers at 2000MB. Unix is usually more proficient in the use of its memory, especially when dealing with network services. Because Unix requires less memory and processor time than Windows NT, a Unix based system has more memory and processor power for other computer functions.

Performance:

With Unix and Windows NT running on standard PC's, Unix ran 27% faster than Windows NT when reading static HTML content, and with API generated content, Unix is between 47% and 197% faster. For CGI contents, Unix is 77% faster than Windows NT.

Internet Services:

Unix has included things such as SMTP (Email), NNTP (News), Telnet, and DNS. All of these protocols and services were somehow forgotten by Windows NT. They can be covered up with third party products and Microsoft's own programs. However, none of these programs and products can compare to Unix in terms of flexibility and power.

Price Comparison:

With the Unix server's cost at approximately one fourth that of the Windows NT, it allows us to provide you with a more cost effective and powerful way to be on the Internet.

Windows or Unix page fault?
Windows XP, 2000 and even NT now outnumber Unix variants in terms of numbers shipped, although that's hardly surprising when you consider that millions of businesses worldwide have moved up to a Microsoft server system from almost nothing. That is - they've upgraded to a client/server system from a simple setup of PCs around an office which either weren't networked at all, or which were only networked via a loosely organised MS "peer to peer" network configuration.
For these sorts of businesses, installing one or more Microsoft servers would be a major step forward. And XP/W2K/NT (and their applications) have the obvious advantage of having fully-blown, comprehensive menu-driven interfaces that look (at first glance) fairly easy and user-friendly. All in all, it's a setup that comes across as a "nice, safe, and solid" option for the average small organisation that needs centralised Internet access onto a LAN.

The operating system that you use on your desktop computer (the vast majority of people use some flavor of Windows) has absolutely nothing to do with the one that your host needs to serve your web site. Most personal sites are created with MS FrontPage and even although that is a Microsoft product, it can be hosted perfectly on a UNIX web server with FrontPage Extensions installed.
Here are some important comparative features that help you determine the kind of hosting required for your website.
Stability:
UNIX systems (we actually use Linux but for comparison purposes they are identical) are the hands-down winner in this category. There are many factors leading to this, to name a few:
UNIX handles high server loads better than Windows
UNIX machines seldom require reboots while Windows is constantly in need of the same.
Servers running on UNIX enjoy extremely high up-time and high availability/reliability
Performance:
Though there is some debate about which operating system performs better, in our experience
Both perform comparably well in low-stress conditions
UNIX servers are superior to Windows under high load (which is what is more important)
Scalability:
Web sites usually change over time, with most of them starting off small and growing with the increasing needs of the person or organization running them. While both platforms can often adapt to your growing needs,
Windows hosting is more easily made compatible with UNIX-based programming features like .
Compatibility:
Web sites that are designed and programmed to be served under a UNIX-based web server can easily be hosted on a Windows server, whereas the reverse is not always true. This makes programming for UNIX the better choice.
Conclusion:
To sum it up,
The UNIX-based web hosting is more stable, performs faster and more compatible than Windows-based hosting.
You only need Windows hosting if you are going to develop a website in .NET or Visual Basic, or any other application that limits your options.