There are actually 234 listed IT companies but I chose to publish only the top 200. The combined market cap of the top 200 IT companies is 253499 crores as of APR 23 2009.

Infosys topped the list in terms of the market cap though TCS tops the revenues list. Wipro and HCL followed the list. iFlex which is renamed to Oracle Financial infosys-logo Services is 5th in the list with a market cap of 7566 crores.

Tech Mahindra has a market cap of 4049 crores and Satyam has a market cap of 3184 crores. Together they have a market cap of 7233 crores. This is around 300 crores less than Oracle Financial Services. The integrated company of Tech Mahindra + Satyam stands at 6th position.

In all probability that will move further up as the financial situation of Satyam looks better than what the papers tell. Of the top 10 Indian IT stocks only Satyam is the most volatile stock and it can gain few percentage points and change the whole equation. (source)

Top 200 IT companies in India by Market Cap :

S.No Companies Market Cap in Crores
1 Infosys Tech 83024.21
2 Tata Consult 55579.59
3 Wipro 45845.61
4 HCL Techno. 8580.78
5 Oracle Finl. 7566.75
6 Mphasis 4741.76
7 Educomp Solu 4485.72
8 Tech Mahindr 4049.96
9 Sterling Int 3495.03
10 Satyam Comp 3184.18
11 Finan.Techno 3076.69
12 Patni Comp. 1967.62
13 HCL Infosys. 1597.69
14 Tulip Telec. 1393.02
15 Rolta (I) 1334.11
16 Moser-Baer 1084.69
17 Redington 1013.48
18 MindTree 935.18
19 Core Project 900.88
20 Cambridge So 798.52
21 Firstsource 727.92
22 CMC 720.46
23 Geodesic 691.5
24 Polaris Soft 651.65
25 Infotech En. 607.14
26 Cranes Soft. 561.21
27 3i Infotech 547.15
28 ICSA (I) 538.28
29 Tanla Solut. 533
30 Vishal Infor 501.96
31 Allied Digital 484.35
32 Hexaware Technologies 467.42
33 Aptech 447.91
34 NIIT 443.18
35 Mastek 410.49
36 NIIT Tech. 387.91
37 Glodyne Tech 373.96
38 Take Sol. 343.2
39 Tata Elxsi 326.35
40 eClerx Serv. 319.65
41 Bartronics 305.01
42 KPIT Cum.Inf 295.05
43 Hinduja Vent 283.55
44 HTMT Global 277.39
45 MIC Electron 272.26
46 Zenith Info. 246.7
47 Everonn Syst 246.15
48 Zensar Tech. 242.71
49 Zylog System 231.37
50 Sonata Soft. 223.02
51 GSS America 203.96
52 Sasken Comm. 199.26
53 Nucleus Soft 198.91
54 Aztecsoft 196.7
55 Northgate Te 159.52
56 Accentia Tec 143.51
57 KLG Systel 138.88
58 Mascon Globl 133.52
59 Aurion.Sol. 128.76
60 D-Link (I) 127.8
61 Geometric 117.77
62 Micro Tech 107.02
63 Tele Data In 103.16
64 Subex 102.95
65 IOL Netcom 99.76
66 Net 4 99.75
67 Octant Inter 98.72
68 Zen Tech. 98.07
69 Genesys Intl 96.23
70 LGS Global 94.82
71 Aftek 92.1
72 Prithvi Info 90.67
73 Megasoft 88.54
74 Info-Drive S 87.72
75 Parle Softwr 87.43
76 Jetking Info 87.03
77 Ramco System 83.8
78 IKF Technolo 82.34
79 Omnitech Inf 81.99
80 R Systems In 81.84
81 Kernex Micro 80.63
82 Spice Mobile 79.74
83 Vakrangee Sf 78.11
84 Datamatics 77.08
85 Tricom India 67.69
86 Four Soft 62.3
87 Logix Micro. 61.46
88 Spanco 59.58
89 Helios & Mat 55.58
90 Softsol (I) 54.89
91 Religare TG 53.78
92 Blue Star In 52.5
93 Sparsh BPO S 49.5
94 Spel Semicon 46.75
95 IT People 44.67
96 Allsec Tech. 44.17
97 Tera Softwar 43.91
98 Mro-Tek 41.66
99 Compucom Sof 40.69
100 Kale Consul. 39.93
101 FCS Software 39.68
102 HOV Services 39.16
103 Dhanus Tech 35.61
104 Indo Pac.Sof 35.38
105 Tutis Tech 34.42
106 South. Onlin 34.31
107 Ajel Infotec 32.63
108 Silverline T 31.15
109 Moschip Semi 30.28
110 Goldstn.Tech 30.01
111 TVS Electron 29.92
112 Nagreeka Cap 29.59
113 Zenith Comp. 27.88
114 Cambridge Tc 27.37
115 Edserve Soft 27.26
116 Trigyn Tech. 27.23
117 Axis IT & T 25.35
118 Sanraa Media 23.92
119 Cybertech Sy 23.9
120 Californ.Sof 23.56
121 Maars Soft 23.48
122 PCS Tech. 22.53
123 Kaashyap Tec 22.26
124 Intense Tech 21.47
125 Avantel Soft 20.6
126 Maestros Med 20.57
127 SQL Star Int 20.21
128 ABM Knowledg 20
129 Brels Info. 19.26
130 Mindteck 19.01
131 Sankhya Info 17.98
132 Compuage Inf 17.3
133 ASM Tech. 17.23
134 Visesh Info 17.2
135 Pan (I) Corp 17.14
136 Melstar Info 17.06
137 ORG Informat 16.57
138 Quintegra So 16.57
139 Visu Intnl. 16.33
140 Onward Techn 16.31
141 Intelvisions 16.31
142 Cerebra Inte 14.96
143 VJIL Consult 14.93
144 Pentasoft Te 14.61
145 Powersoft Gl 14.15
146 Firstobject 13.85
147 Virinchi Tec 13
148 Cat Technol. 12.88
149 Compulink Sy 12.44
150 Accel Trans 12.43
151 IEC Educat. 12.31
152 Triton Corp 12.19
153 Luminaire Te 12.12
154 Cybermate In 11.07
155 RS Software 10.93
156 Interworld D 10.91
157 Silverline A 10.65
158 Usha Mar.Inf 10.52
159 Ranklin Sol. 10.41
160 S Kumars Onl 9.6
161 Lee&Nee Soft 9.09
162 Shreejal Inf 8.63
163 Zigma Soft. 8.54
164 Birla Shloka 8.32
165 TeleCanor Gl 8.2
166 Sark Systems 8.08
167 Vama Inds. 7.92
168 BITS 7.61
169 Software Tec 7.59
170 VXL Instrum. 7.56
171 Crazy Infote 7.55
172 Allied Comp. 7.41
173 Solix Tech. 7.36
174 Computech In 7.26
175 Ram Informat 7.01
176 Saarc Net 6.89
177 CSS Techn. 6.67
178 Dynacons Sys 6.66
179 Comp-U-Learn 6.36
180 ACE Software 6.13
181 Platinum Cor 5.89
182 Nexxoft Info 5.82
183 Sylph Tech. 5.79
184 Contech Soft 5.78
185 Cressanda So 5.73
186 Ontrack Syst 5.72
187 Valuemart In 5.61
188 Infotrek Sys 5.33
189 Odyssey Tech 4.89
190 Advent Comp. 4.88
191 Kashyap Tele 4.77
192 Kushagra Sof 4.72
193 CG Vak Soft. 4.55
194 Prithvi Soft 4.5
195 Twinstar Sof 4.5
196 Libord Info 4.4
197 Computer Pnt 4.34
198 Chakkilam In 4.3
199 Svam Softwar 4.05
200 T Spiritual 3.84