Microsoft's latest operating system Windows 7 opened to rave reviews last week. After the dismal performance of its earlier operating system Vista, Microsoft seems to be heaving a sigh of relief at the grand reception that its new OS has received.

PC makers are scrambling to offer Windows 7-based systems, including Netbooks, as they hope the operating system to spur PC sales. After skidding for six months, computer shipments have shown some improvements recently. Seems Microsoft is all set to further strengthen its grasp over computer desktops.

Not really! As many skeptics beg to differ. According to them, Vista too got high marks before its release as well, with writers praising the new visual design and glossing over quirks that later became common gripes.

Here's looking into what may dampen Microsoft's Windows 7 party.

One of the biggest complain that most analysts have is the lack of direct upgrade from XP, the operating system which still continues to run on almost 80% of the world's computers. Windows 7 fails to offer a smooth transition from XP as there is no upgrade option. Users will have to go for a fresh install.

Writes Tony Bradley of PC World, "After the issues with Windows Vista, and knowing that the vast majority of users-both consumer and enterprise-are still relying on Windows XP, it seems like a direct upgrade path is a necessity. Many users may be frustrated by the lack of upgrade path and having to do a fresh install, reinstall all of the other software and migrate user settings. Microsoft has provided tools to ease the pain, but this is still the biggest opportunity for negative PR or backlash related to Windows 7."

According to Microsoft, the upgrade option is not available in Windows 7 Setup when installing Windows 7 on a computer running Windows XP. However, users can use Windows Easy Transfer to migrate files and settings from Windows XP to Windows 7 on the same computer.

The basic requirements of a PC to run on Windows 7 are 1 GHz processor, minimum 1GB of RAM and 16GB hard drive space. This in simple words means any hardware that worked with Vista will work for Windows 7 too.

However, one of the most crucial reasons for Vista not succeeding was that the operating system almost forced a hardware upgrade on users. Hope the almost similar requirement does not hamper the prospects of Windows 7. It's is also to be noted here that that the basic PC configuration has seen a jump since Vista days.

According to Bradley, Windows Vista stumbled due to the lack of hardware and device driver support. He writes, "The vendors just weren't ready when Vista was launched and Vista never really recovered from the damaged reputation even after most of those issues were resolved."

It is not a great experience for users working on a new operating system to find out that their existing printer, wireless router, webcam, and other peripheral hardware devices don't work with the new OS. This means either they stop working on that hardware or look for new hardware that is compatible.

The most controversial and much maligned feature of Vista, UAC or User Account Control is a part of Windows 7 too. The UAC was designed to prevent unauthorised execution of code by displaying a pop-up warning every time a change is being made to the system, whether by the operating system or a third-party application.

Many Vista users complained of being bombarded with the warnings. It proved a huge annoyance for users installing new applications frequently. Windows 7 now allows you to set the level of information that a user desires.

However, writes Bradley, "... still after much debate with the security community during the Beta testing, the default setting is still set to what users experienced with Windows Vista. Frankly, UAC serves a purpose and it is better to leave it alone. But, those who dislike UAC are going to have to go into the control panel and modify the configuration to their liking or be faced with the same pop-ups that annoyed the world with Vista."