After three years and a half GTA comeback to PC.
Windows Vista Ultimate x64
3 GB RAM DDR 2 667 Mhz
Core 2 Duo E8400 at 3.0 Ghz
Geforce GTX 260
Generic Intel media series motherboard
X-fi Xtremegamer Pro
With the above rig I could play this game at 1440x900 with the default detected settings without trouble. (average high but not very high)
Warning! GTA series is about single player if you plan to buy GTA 4 for multiplayer you're in the wrong game.
What I can say about GTA 4 that is not already said?
The sandbox genre is one of te most seek genres by the developers when GTA 3 was released a bunch of developers/studios launched to create sandbox games. After many years still the only true amazing series in that genre is GTA, Rockstar becomes a master in the genre with nice attempts made by Ubisoft and EA but neither had come close to Rockstar masterpieces.
When you walk trough Liberty City streets you find a huge ficticious city with a lot of marketing banners, traffic, pedestrians, radio stations, tv channels (with commercials too), entertainment sites, restaurants, hidden characters, cool cars, activities and its own serial killer!!!. The missions are like always a lot of variety,fun and funny with a couple with a nice slice of action.
Another good point of GTA 4 against its predecessors its that is less huge than San andreas and omits the boring paramedic,pizza and firefighter missions.
From the three different versions that exists the weaker is the PC version but at least (thanks rockstar) was released (other studios doesn't release PC games anymore). For a plus GTA 4 PC adds nice graphics, a video recorder, you can use your own mp3s and that's all, also uses the same achievements than xbox 360 version.
GTA for PC requires that you install before Games for windows client (today it's a little common but games that use it continue growing), also requires Rockstar club installation. Many users complain about the installation of both programs however the installation and creation of accounts its very straight forward (my bet is that only the pirates complain about it)
some advice before install it:
1º Be aware! that you need to avoid install it in many PC multiple times, right now has an annoying activation limit problem. If you burn all your activations you need to call to MS and wait 3 days for recive another key and this process you can do it only 1 time.
(Still in November 2009 MS is trying to addressing this concern in the next Games for Windows client update)
2º Don't try it to run it in a low specs PC or a limited laptop with old video chipset or intel integrated video.
3º Rockstar is newbie creating multiplayer games so the PC version is full of hackers and cheaters and that convert it into a desert.
4º Be sure you defragment your disk and disable your antivirus before install it... becomes in two dual layer DVDs. (I could install it in less than 15 mins. but if you don't follow my advice you can spend a nice hour waiting)
Sad to say but If you're a strict console player don't look for the PC version it's not worth it, but if you're like me a strict PC player you should try it the single player is awesome GTA 4 is the best sandbox game released on years (indeed since GTASA).
Something good about the PC is that in the next years when XBOX 360 and PS3 become obsolete and next versions will not have backward compatibility (the most probable) you are going to still play the PC version of GTA 4 at full graphics.